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DOI: 10.1055/a-2136-3609
Acetate/Alkoxide/Halide Shuttle Systems Mediated by Lewis Acid Catalysts for Insertion Reaction of a One-Carbon Unit into Carbon–Carbon or Carbon–Halogen Bonds
This work was supported by the Core Research for Evolutional Science and Technology, Core Research for Evolutional Science and Technology (JST CREST; Grant Number JPMJCR20R3), Japan, and a Grant-in-Aid for Transformative Research Areas (A) (21H05212) Digitalization-driven Transformative Organic Synthesis (Digi-TOS) from the Ministry of Education, Culture, Sports, Science & Technology, Japan. It was also supported by Japan Society for the Promotion of Science (JSPS) KAKENHI (grant number JP19K05455).
Abstract
In this account, we describe our research on a Lewis acid-catalyzed insertion reaction of α-diazo esters into a carbon–carbon or carbon–halogen bond. Indium catalysts mediated not only the insertion of α-diazo esters into a carbon–carbon bond of alkyl acetates, alkyl ethers, acetals, and alkyl halides, but also a carbon–halogen bond of alkyl chlorides, bromides, and iodides. BF3 specifically accelerated the insertion of α-diazo esters into a carbon–fluorine bond. The key to this catalysis is acetate, alkoxide, and halide shuttle systems mediated by a Lewis acid, in which the Lewis acid abstracts a leaving group from a starting substrate and releases the leaving group to the appropriate carbocation intermediate in the catalytic cycle.
1 Introduction
2 Acetate/Alkoxide Shuttle: Insertion Reaction of α-Diazo Esters into a Carbon–Carbon Bond of Alkyl Acetates, Alkyl Ethers, and Acetals
3 Halide Shuttle: Insertion Reaction of α-Diazo Esters into a Carbon–Carbon Bond of Alkyl Halides
4 Halide Shuttle: Insertion of α-Diazo Esters into a Carbon–Halogen Bond of Alkyl Halides
5 Conclusion
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Key words
insertion reactions - C–C bonds - C–halogen bonds - diazo compounds - Lewis acids - alkyl acetates - alkyl ethers - acetals - alkyl halidesBiographical Sketches
Yoshihiro Nishimoto received his Ph.D. degree in 2009 from Osaka University under the supervision of Prof. Akio Baba. He was appointed Assistant Professor at the Department of Applied Chemistry of Osaka University in 2009. In 2014, he moved to the Frontier Research Base for Global Young Researchers, Center for Open Innovation Research and Education (COiRE). He then became an Associate Professor (2020) at the Department of Applied Chemistry of Osaka University. His research interests include the development of Lewis acid-catalyzed reactions, novel main-group metal catalysts, and photocatalysis.
Makoto Yasuda received his Ph.D. degree in 1995 from Osaka University under the guidance of Prof. Akio Baba, and he was appointed Assistant Professor. During 1998–1999, he worked with Prof. J. M. Stryker as a postdoctoral fellow at the University of Alberta. After returning to Osaka University, he was promoted to Associate Professor in 2004 and full Professor in 2014. He is currently interested in organic synthesis using main group metals, and in the development of new types of Lewis acids with a designed organic framework. He is also investigating reactive metal species that contribute to stereoselective carbon–carbon bond formation and their characterization based on spectroscopy and X-ray crystallographic analysis.
Introduction
The insertion reaction of a carbon unit into a chemical bond involving a carbon atom realizes the simultaneous formation of two chemical bonds around the carbon unit to enable access to structurally complex organic compounds in a step-economic way. Thus, numerous studies on various chemical bonds undergoing insertion, such as carbon–hydrogen, carbon–carbon, and carbon–heteroatom bonds, have been conducted. In early research, the insertion of reactive naked carbene species into various chemical bonds were revealed.[1] However, this methodology using reactive naked carbenes is not suitable for fine organic synthesis due to poor chemoselectivity. Thus, insertion reactions using transition-metal carbenoides with high chemoselectivity has been gaining attention.[2] In addition, various transition-metal catalyses involving migratory insertion of alkenes, alkynes, and carbon monoxide have been established.[3] Diazo compounds can be used as mild carbene equivalent reagents for chemoselective reactions.[4] Maruoka’s group and others reported Lewis acid catalyzed insertion of diazo compounds into (O)C–C or (O)C–H bonds in ketones or aldehydes, respectively.[5] The development of new strategies for the insertion reaction, therefore, has been of significance in organic chemistry.
We have studied Lewis acid-catalyzed substitution reactions of HO, MeO, AcO, Me3SiO, and Cl groups with organosilicon nucleophiles (Scheme [1]A).[6] [7] Moderate Lewis acid catalysts such as heavy main-group metal salts, InX3 and GaX3, exhibit efficient catalytic activity. The moderate Lewis acidity is a vital factor to complete the catalytic substitution reactions. These Lewis acid catalysts can activate oxygen-containing substrates to abstract a leaving group, generating carbocation intermediates. In addition, the catalysts can be regenerated by releasing the leaving group. If the Lewis acidity is high, the Lewis acid can abstract but cannot release a leaving group, which prevents a catalytic cycle. On the basis of our previous studies on moderate Lewis acid catalysts, we draw a working hypothesis for an insertion reaction of a diazo compound into a chemical bond catalyzed by a Lewis acid (Scheme [1]B). A Lewis acid abstracts a leaving group (X) to provide a carbocation, which reacts with a diazo compound to generate diazonium intermediate. Then, N2-elimination, migration of a carbon substituent (blue-colored C), and re-composition of a C‒X σ-bond completes an insertion of a one-carbon unit (black-colored C) into a carbon–carbon bond. On the other hand, another reaction path composed of N2-elimination and nucleophilic attack of X– without the migration leads to an insertion into a C–X bond. In this account, we describe insertion reactions of α-diazo esters into carbon–carbon or carbon–halogen bonds based on our working hypothesis. Abstraction and release of an AcO or MeO group by a Lewis acid (acetate/alkoxide shuttle) realized the elongation of alkyl acetates, alkyl ethers, and acetals with α-diazo esters via carbon–carbon bond insertion (Scheme [2]A and B).[8] The halide shuttle system achieved two types of elongation of alkyl halides via carbon–carbon or carbon–halogen bond insertion (Scheme [2]C and D).[9] [10] [11]
# 2
Acetate/Alkoxide Shuttle: Insertion Reaction of α-Diazo Esters into a Carbon–Carbon Bond of Alkyl Acetates, Alkyl Ethers, and Acetals
Our group revealed the unique catalytic activity of a combination of indium trihalides with silyl halides in the substitutions of HO, AcO, and Me3SiO groups.[6] Therefore, we examined the insertion reaction of α-diazo esters into a carbon–carbon bond of alkyl acetates (Scheme [2]A) by the use of the In/Si Lewis acid catalysts (Table [1]).[8] In the examination of the reaction of benzhydryl acetate 1 with α-diazo ester 2a, the combination of InI3 with Me3SiBr led to the expected insertion reaction, giving the elongated product 3 in 67% yield with high diastereoselectivity (90:10) (entry 1). The sole use of either InI3 or Me3SiBr did not work (entries 2 and 3). Reduced loading of catalyst led to a poor result (entry 4). Other combinations, InI3/Me3SiCl and InI3/Me3SiBr led to lower yields than that with InI3/Me3SiBr (entries 5 and 6).
a Reaction conditions: 1 (0.5 mmol), 2a (1.0 mmol), CH2Cl2 (1 mL), room temperature, 2 h.
Benzylic ethers also undergo this insertion reaction with an α-diazo ester (Scheme [3]). Benzhydryl ether 4a gave the desired product 5a with a high level of stereoselectivity, although the yield was only 18%. The reaction of triphenylmethyl ether 4b proceeded smoothly without the addition of Me3SiBr to give the elongated product 5b in 89% yield.
Doyle and co-workers reported the elongation of acetals with α-diazo esters catalyzed by BF3·OEt2,[12] [13] but the scope of suitable acetals and α-diazo esters was very limited. Thus, we attempted to establish a more versatile system with an alkoxide shuttle mediated by indium catalyst (Scheme [2]B). After further investigation, the use of 10 mol% of InBr3 completed the insertion of α-diazo ester 2b into a C–C bond of benzaldehyde dimethyl acetal to give an excellent yield of 7a, as shown in Scheme [4]. Various acetals derived from indole-3-carbaldehyde, furan-3-carbaldehyde, and thiophene-3-carbaldehyde were suitable for this reaction, giving the corresponding elongated products 7b–d in high yields. The reaction of an acetal derived from an α,β-unsaturated aldehyde proceeded smoothly with retention of the stereochemistry of the alkene moieties (7e). The elongation of a cyclic acetal, which is more stable than the corresponding dimethyl acetal, was accomplished under the optimal conditions (7f).
Notably, the scope of α-diazo esters 2 in the elongation of acetal 6a is considerable (Scheme [5]). For example, α-phenyl α-diazo ester 2c was a feasible substrate to furnish the corresponding product 7g in 92% yield. The reaction using α-alkyl α-diazo ester 2d gave a moderate yield of the desired product 7h. α-Diazo sulfone 2e, as an alternative to diazo esters, was an applicable substrate to give the desired sulfone product 7i.
Acetals derived from ketones as well as aldehydes were applicable (Scheme [6]). In the reaction of methyl phenyl ketone acetal 6b, α-phenyl ester product 7j was obtained in 91% yield. In addition, the use of alkenyl methyl ketone acetal 6c gave α-alkenyl ester 7k in 39% yield. In both cases, α-diazo ester 2b was selectively inserted into (MeO)2C–C(sp 2) bonds. The (MeO)2C–C(sp) bond of alkynyl methyl ketone acetal 6d underwent the insertion selectively to yield α-alkenyl ester 7l.
A plausible mechanism for the insertion of α-diazo ester 2a into a C–C bond of alkyl acetate 1a via acetate shuttle is shown in Scheme [7]A. A Br atom of Me3SiBr coordinates to InI3 and the Lewis acidity on the Si atom is increased (A). Since the Lewis acidity of InI3 is not high enough to abstract AcO or MeO group, which is a poorer leaving group than halide groups, the activation of alkyl acetates or ethers requires the combination of InI3 with Me3SiBr, which exhibits a higher Lewis acidity than InI3.[6] The AcO group coordinates to the Si center, then abstraction of the AcO group occurs to generate carbocation C and InI3-Me3SiBr-OAc ate complex D.[14] The electrophilic addition of cation C to α-diazo ester 2a gives diazonium E. The migration of a Ph group to the diazonium carbon and concerted denitrogenation proceeds to generate benzyl cation intermediate F. The AcO–, which is captured by Me3SiBr-InI3 complex, attacks the carbocation intermediate F to give elongated product 3a, and InBr3 and Me3SiBr are regenerated. The diastereoselectivity would be determined at the nucleophilic addition of AcO– to the carbocation intermediate. Scheme [7]B shows the reaction mechanism of elongation of acetal 6b via InBr3-mediated alkoxide shuttle. InBr3 abstracts MeO– from 6b to give oxonium ion H. Then, the electrophilic addition of H to 2b affords diazonium I. The migration of the Ph group occurs in preference to the Me group, and at the same time N2 is eliminated to generate the oxonium intermediate J. The nucleophilic attack of MeO– in InBr3(OMe)– gives elongated acetal product 7j. The migration magnitude is the same as that in semipinacol migration because alkenyl and alkynyl groups migrate preferentially.[15] An indium catalyst can conduct the AcO/MeO shuttle by abstracting the RO– (AcO– or MeO–) group from a substrate (alkyl acetates, alkyl ether, or acetals) and returning RO– to cationic intermediates (carbocations or oxonium ions) due to its moderate Lewis acidity.
# 3
Halide Shuttle: Insertion of α-Diazo Esters into a Carbon–Carbon Bond of Alkyl Halides
In order to substantiate the working hypothesis for the halide shuttle system to achieve an insertion reaction of α-diazo esters into a carbon–carbon bond of alkyl halides (Scheme [2]C), the reaction of diphenylmethyl chloride 8a with α-diazo ester 2a was examined (Table [2]).[9] When InCl3 catalyst was used in CH2Cl2,[6d] [e] the insertion reaction proceeded to the corresponding product 9a in 70% yield (entry 1). In this case, the diastereomeric ratio was moderate (75:25). Other group-13 Lewis acids, AlCl3 and BF3·OEt2, gave no products (entries 2 and 3). The use of ZnCl2 or SnBr4 [16] were effective to give 9a in 66 and 63% yields, respectively, but the diastereoselectivity was poor in comparison to that of InCl3 (entries 4 and 5). After investigating the effect of solvents, ethyl acetate was found to afford the highest diastereoselectivity. Finally, the adoption of InCl3 catalyst, low temperature, and dilute conditions led to the highest diastereomeric ratio (95:5) (entries 6–12).
a Reaction conditions: 8a (0.5 mmol), 2a (0.6 mmol), catalyst (0.05 mmol), solvent (1 mL), 0 °C, 5 min and then room temperature, 2 h.
b The reaction was carried out with 2a (1.0 mmol) in EtOAc (2 mL) at 0 °C for 6 h.
This reaction system is applicable to various diarylmethyl chlorides 8 and α-diazo esters 2 (Scheme [8] and Scheme [9]). For example, diarylmethyl chloride substrates with electron-donating groups such as MeO and Me groups gave the corresponding C–C bond insertion products 9b and 9c with high diastereoselectivity. A C(sp 2)–Cl bond was also tolerated (9d), although the steric hindrance of an o-Me group decreased the diastereoselectivity (9e).
When α-diazo esters bearing terminal alkenyl and alkynyl groups were used (Scheme [9]), these carbon–carbon multiple bonds were intact and the desired products 9f, 9g were smoothly obtained. α-Alkyl- or α-aryl-substituted α-diazo esters other than simple diazo ester 2a were successfully employed to construct α-quaternary carbon esters 9h, 9i with high diastereoselectivity.
The reaction using unsymmetrical diarylmethyl chloride 8b provided significant information on the reaction mechanism (Scheme [10]). The electron-rich aryl group (4-MeC6H4) migrated preferentially, rather than an electron-deficient group (4-ClC6H4). This result indicates that the reaction path involves Wagner–Meerwein migration of an aryl group in a carbocation intermediate and an electron-donating group has a positive effect on aryl migration.[17]
A plausible reaction mechanism for the chloride shuttle mediated by InCl3/InCl4 – catalysis is illustrated in Scheme [11]. InCl3 abstracts Cl– from diphenylmethyl chloride 8a to afford benzylic cation B, and then the reaction of cation B with α-diazo ester 2a proceeds to generate diazonium intermediate C. The intermediate C affords benzylic cation D through three-membered ring transition states in which concerted Ph-migration and N2-elimination takes place. The addition of Cl– from InCl4 – to the cationic carbon centers occurs antiperiplanar to the Ph group at the α-position of the carbonyl group to give the final product 9a. The origin of diastereoselectivity and the solvent effect was investigated by DFT calculations and isomerization experiments.[9] The diastereoselectivity is determined at the addition of Cl– into cation D or D′. Since the conformer D′ is less stable than D due to the repulsion between Ph and CO2Et groups, conformer D preferentially gives the product in high diastereoselectivity. The moderate donor solvent EtOAc inhibits the isomerization of diastereomers via a retro-reaction.
The insertion into a C–C bond via bromide or fluoride shuttle was successful (Scheme [12]). InBr3 mediated the reaction of diphenylmethyl bromide 10 with α-diazo ester 2a to afford the desired β-bromo ester product 11 in high diastereoselectivity and high yield. For diphenylmethyl fluoride 12, the use of BF3·OEt2 is essential for the fluoride shuttle (vide infra), and β-fluoro ester 13 was obtained in excellent diastereoselectivity.
The present chloride shuttle system realized a ring expansion of fused polycyclic chloride compounds (Scheme [13]).[18] Dihydrodibenzo[b,f]oxepine derivatives 15 and -dihydrodibenzo[b,f]thiepine derivatives 17 were successfully synthesized from 9-chloro-9H-xanthene 14 and 9-chloro-thioxanthene 16, respectively, by treatment with α-diazo ester 2a and InCl3. The ring expansion of 5-chloro-10,11-dihydro-5H-dibenzo[a,d][7]annulene 18 gave tetrahydro-dibenzo[a,e]cyclooctene 19 in 79% yield. The present strategy for the construction of fused cyclic structures has significance for pharmaceutical chemistry.[19]
# 4
Halide Shuttle: Insertion of α-Diazo Esters into a Carbon–Halogen Bond of Alkyl Halides
In insertion systems of α-diazo esters into C–C bonds of diarylmethyl acetates and halides as mentioned above, the generation of a more stable benzylic cation is the driving force for the migration of an aryl group (Scheme [14], upper). If this driving force is absent, the Ar-migration will be hampered and X– will eliminate N2 to complete an insertion into a C–X bond (Scheme [14], lower). Based on this hypothesis, we achieved the insertion of α-diazo esters into C–F, Cl, Br, and I bonds as shown in Scheme [2]D. [10] [11]
The development of selective transformation of a C–F bond is an important issue in organic chemistry.[20] The insertion reaction of a one-carbon unit into a C–F bond, however, remains underdeveloped.[21] We examined the reaction of benzylic fluoride 20a with α-diazo ester 2f by using various Lewis acids, which are known to abstract a fluoride from alkyl fluorides (Table [3]). To our delight, BF3·OEt2 [22] produced C–F insertion product 21a in 33% yield with moderate diastereoselectivity, while the progress of a C–C bond insertion was not observed (entry 1). Stronger Lewis acids such as B(C6F5)3,[23] AlCl3,[24] and Me3Al[25] did not work (entries 2–4).[26] The use of B(C6F5)3 or AlCl3 resulted in complex mixtures of products while 20a was completely consumed (entries 2 and 3). Me3Al resulted in the recovery of the starting material (entry 4) and the use of InCl3 gave no product (entry 5). Rh2(OAc)4,[27] AgOTf,[28] and Cu(OTf)2,[29] which mediate reactions via metal carbenoids, were also ineffective (entries 6–8). Finally, dilute conditions with PhCl as solvent at –44 °C gave the best yield and the best diastereoselectivity (entry 9).
A diverse range of benzylic fluorides 20 smoothly underwent the desired insertion reaction (Scheme [15]). A C(sp2)–Br bond was tolerated under these reaction conditions to give a high yield of 21b. AcO and phthaloylamino groups, which are useful functional groups in the downstream synthesis, were available (21c and 21d). The excellent result from the reaction using 21e suggested efficient compatibility with an alkyl chloride moiety.
This reaction system offers excellent diversity of α-aryl diazo esters 2 (Scheme [16]). Diazo esters with halogeno groups on the benzene rings gave high yields, in which C–Br and C–I bonds were intact (21f and 21g). The Bpin group remained intact in this reaction system (21h). This functional compatibility is beneficial in organic synthesis, such as for the synthesis of substrates for Suzuki–Miyaura cross-coupling reaction. α-Diazo esters with electron-deficient aryl groups also furnished the corresponding products 21i and 21j.
a Reaction conditions: 20a (0.2 mmol), 2f (0.3 mol), catalyst (0.02 mmol), solvent (1 mL), 4 h.
b Solvent (2 mL).
The outline of a catalytic cycle is shown in Scheme [17]. F– is abstracted by BF3 from benzylic fluoride 20, and then the corresponding benzylic cation intermediate B is generated. The reaction between cation B and α-diazo ester 2 generates diazonium intermediate C. Elimination of N2 followed by the BF4 –-mediated reformation of a C–F bond (D)[30] occurs to complete the fluoride shuttle system, providing α-fluoro ester product 21.
DFT calculations clarified the reaction mechanism involving the fluoride shuttle and the origin of the high diastereoselectivity. The energy profile of the reaction between benzylic fluoride 20b and α-diazo ester 2f is illustrated in Scheme [18]. A fluorine atom in 20b interacts with BF3 and then is abstracted to generate benzylic cation intermediate 24 and BF4 –. The activation barrier in the cleavage of the C–F bond is only 5.92 kcal/mol due to thermodynamic stability of BF4 –. Then, a C–C formation between the carbocation and 2f in a van der Waals complex 25 proceeds through TS26 to give diazonium intermediate 27. Elimination of N2 then provides carbocation 28 exergonically. The diastereoselectivity is determined during the C–F bond reformation process. Carbocation 28 and BF4 – form contact ion-pairs 29a and 29b. Complex 29a furnishes diastereomer 21k-major through the nucleophilic attack of an F atom in BF4 – to the cationic carbon center (TS30a). Metastable conformer 29b gives diastereomer 21k-minor through a similar reaction path, but the steric repulsion between Ar1 and Ar2 groups makes TS30b less stable than TS30a (Scheme [18], lower). Thus, 21k-major is mainly obtained according to the Curtin–Hammett principle. The successful fluoride shuttle system consisting of C–F bond cleavage and reformation by BF3 is due to its moderate fluoride affinity (FIA: 346 kJ/mol).[31] That is, BF3 can abstract and release F–. Other Lewis acids such as B(C6F5)3 (FIA: 448 kJ/mol) and AlCl3 (FIA: 505 kJ/mol) can abstract F–, but cannot release it, giving complex product mixtures.
We demonstrated the transformation of the obtained α-fluoro esters into fluorine analogues of bioactive or pharmaceutical compounds (Scheme [19]). α-Fluoro ester 21l was synthesized by BF3-catalyzed diastereoselective elongation of 20c with 2g. Hydrolysis of 21l followed by amidation with guanidine achieved the synthesis of fluoro-analogue 31 of compound 32, which can function as a transient receptor potential canonical channel (TRPC channel) inhibitor.[32] This demonstration illustrates the significance of the present insertion reaction in organic synthesis.
In contrast to the fluoride shuttle system, BF3 was not effective for the chloride shuttle system in the reaction of benzylic chloride 33a with α-diazo ester 2f at all (Table [4], entry 1). Our group reported the catalytic activity of indium halides for the cross-coupling reaction between alkyl halides and organosilicon nucleophiles in which InX3 abstracts X– from alkyl halides and generates carbocation intermediates.[6] The use of InCl3 instead of BF3·OEt2 was found to be effective in the desired reaction, giving product 34a in 75% yield (entry 2). Unfortunately, conditions to provide a high diastereomeric ratio could not be found. Other group-13 metal Lewis acids, AlCl3 and GaCl3, showed no catalytic activity (entries 3 and 4). Other typical Lewis acids, ZnCl2, FeCl3, SnCl4, and BiCl3 gave moderate yields, but their catalytic activities were less than that of InCl3 (entries 5–8).
a Reaction conditions: 1a (0.4 mmol), 2a (0.5 mmol), catalyst (0.04 mmol), solvent (1 mL), 0 °C, 4 h.
For a wide variety of benzylic chlorides, InCl3 works well in the present elongation (Scheme [20]). A C(sp2)–Br bond and an acetal moiety were tolerated under the reaction conditions (34b, 34c). An electron-rich benzylic chloride possessing an alkyl group was available to afford a good yield of 34d. A CF3 group on the benzene ring retarded the reaction due to the instability of the corresponding benzylic cation intermediate (34e). An indole substrate was well accommodated (34f). Almost all diastereomers were easily separated using conventional isolation procedures, although high levels of diastereomeric ratios of products were not achieved.
Various functional groups on the benzene ring of α-aryl diazo esters are compatible with the present reaction conditions, including bromine, iodine, ester, and Bpin moieties (Scheme [21]). Electronic perturbation by the substituents on benzene rings has no negative effect on the yields (34g–j). The present reaction system provided an efficient tool to synthesize structurally complex α-alkyl α-aryl α-chloro esters.
A plausible mechanism for the reaction of benzylic chloride 33, α-diazo ester 2, and InCl3 is illustrated in Scheme [22]. InCl3 generates benzylic carbocation B from benzylic chloride by abstracting Cl–. The reaction of B with 2 affords diazonium intermediate C. Elimination of N2 from C generates carbocation D. Cation D undergoes nucleophilic attack of Cl– in InCl4 – to provide product 34 and regenerates InCl3. The reversibility of the C–Cl bond reformation step degrades the diastereomeric ratio, which was suggested by DFT calculations.[11] It is noted that BF3·OEt2 is ineffective for this chloride shuttle system, in contrast to the previous fluoride shuttle system. DFT studies suggest that the abstraction of Cl– from benzylic chloride 33 by BF3 is a considerably uphill process in contrast to InCl3. The soft Lewis acidity of InCl3 can facilitate both the abstraction and release of Cl– to complete the chloride shuttle.
The insertions of α-diazo esters into carbon–bromine and carbon–iodine bonds were also achieved by using InBr3 and InI3, respectively (Scheme [23]).[16] With a catalytic amount of InBr3, benzylic bromides 35 underwent an insertion reaction of α-diazo ester 2f under low temperature conditions to give the corresponding α-bromo ester 36 in high yield. The elongation of benzylic iodide 37 mediated by InI3 took place and α-iodo ester 38 was provided in a moderate yield. To avoid contamination from different halogen groups in the products, the use of InBr3 and InI3 were needed.
The C–Br insertion product 36 can be effectively used in organic synthesis by InBr3-catalyzed substitution reactions (Scheme [24]). The substitution reaction of a bromine atom with N3 – afforded azide 39 in a high yield. Thio ester 40 was also synthesized by InBr3-catalyzed substitution reaction with Me3SiSPh.
# 5
Conclusion
We outlined our developed insertion reactions of α-diazo esters into a carbon–carbon bond of alkyl acetates, alkyl ethers, and alkyl halides, and a carbon–halogen bond of alkyl halides. These reactions constitute a new type of insertion reaction of α-diazo esters into a carbon–carbon bond or a carbon–halogen bond via acetate, alkoxide, or halide shuttle. A Lewis acid abstracts a leaving group (AcO, MeO, F, Cl, Br, or I) from a starting material to generate a carbocation intermediate and provides the leaving group to the appropriate carbocation intermediate at the appropriate step, both of which are vital steps to complete the shuttle system. The adoption of an appropriate Lewis acid catalyst for each shuttle system is quite important: InX3 for acetate, alkoxide, chloride, bromide, and iodide shuttle and BF3 for fluoride shuttle. This new strategy based on the Lewis acid-mediated shuttle system may have significant utility for other challenging reactions involving insertion into carbon–heteroatom bonds.
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Conflict of Interest
The authors declare no conflict of interest.
Acknowledgment
Thanks are due to the Analytical Instrumentation Facility, Graduate School of Engineering, Osaka University.
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- 6l Kita Y, Yata T, Nishimoto Y, Yasuda M. J. Org. Chem. 2018; 83: 740
- 6m Nakao S, Saikai M, Nishimoto Y, Yasuda M. Eur. J. Org. Chem. 2021; 77
- 7a Yadav JS, Antony A, George J, Reddy BV. S. Eur. J. Org. Chem. 2010; 591
- 7b Yang Y.-S, Wang S.-W, Long Y. Curr. Org. Chem. 2016; 20: 2865
- 7c Sestelo JP, Sarandeses LA, Martínez MM, Alonso-Marañón L. Org. Biomol. Chem. 2018; 16: 5733
- 8 Wang F, Yi J, Nishimoto Y, Yasuda M. Synthesis 2021; 53: 4004
- 9 Wang F, Nishimoto Y, Yasuda M. Angew. Chem. Int. Ed. 2022; 61: e202204462
- 10 Wang F, Nishimoto Y, Yasuda M. J. Am. Chem. Soc. 2021; 143: 20616
- 11 Wang F, Nishimoto Y, Yasuda M. Org. Lett. 2022; 24: 1706
- 12 Doyle MP, Trudell ML, Terpstra JW. J. Org. Chem. 1983; 48: 5146
- 13 Ring expansion of cyclic acetals with diazo esters catalyzed by Me3SiOTf: Courant T, Pasco M, Lecourt T. Org. Lett. 2018; 20: 2757
- 14 Liu C, Sang S, Chen F, Yan Y, Zhang C, Huang W. J. Phys. Org. Chem. 2019; 32: e3902
- 15a Wang SH, Tu YQ, Tang M. Comprehensive Organic Synthesis, 2nd ed., Vol. 3. Knochel P. Elsevier; Amsterdam: 2014: 795
- 15b Gouygou M, Urrutigoïty M. Comprehensive Organic Synthesis, 2nd ed., Vol. 3. Knochel P. Elsevier; Amsterdam: 2014: 757
- 16 Modak A, Alegre-Requena JV, de Lescure L, Rynders KJ, Paton RS, Race NJ. J. Am. Chem. Soc. 2022; 144: 86
- 17a Masuda S, Nakajima T, Suga S. Bull. Chem. Soc. Jpn. 1983; 56: 1089
- 17b Li X, Li C, Zhang W, Lu X, Han S, Hong R. Org. Lett. 2010; 12: 1696
- 17c Tsuji Y, Richard JP. J. Phys. Org. Chem. 2016; 29: 557
- 17d Curtin DY, Crew MC. J. Am. Chem. Soc. 1954; 76: 3719
- 17e Cram DJ. J. Am. Chem. Soc. 1964; 86: 3767
- 17f Brown HC, Kim CJ. J. Am. Chem. Soc. 1968; 90: 2082
- 18a Stopka T, Marzo L, Zurro M, Janich S, Würthwein E.-U, Daniliuc CG, Alemán J, Mancheño OG. Angew. Chem. Int. Ed. 2015; 54: 5049
- 18b Zhang C, Jiang H, Zhu S. Chem. Commun. 2017; 53: 2677
- 19a Boegesoe KP, Liljefors T, Arnt J, Hyttel J, Pedersen H. J. Med. Chem. 1991; 34: 2023
- 19b Zhong M, Peng E, Huang N, Huang Q, Huq A, Lau M, Colonno R, Li L. Bioorg. Med. Chem. Lett. 2014; 24: 5738
- 19c Liu H, Liang H, Meng H, Deng X, Zhang X, Lai L. MedChemComm 2018; 9: 239
- 19d Platella C, Capasso D, Roccardi C, Musumeci D, DellaGreca M, Montesarchio D. Org. Biomol. Chem. 2021; 19: 9953
- 19e Zhao S, Zhang H, Jin H, Cai X, Zhang R, Jin Z, Yang W, Yu P, Zhang L, Liu Z. Eur. J. Med. Chem. 2021; 225: 113750
- 19f Cao S, Yang X, Zhang Z, Wu J, Chi B, Chen H, Yu J, Feng S, Xu Y, Li J, Zhang Y, Wang X, Wang Y. Eur. J. Med. Chem. 2022; 230: 114089
- 20a Amii H, Uneyama K. Chem. Rev. 2009; 109: 2119
- 20b Shen Q, Huang YG, Liu C, Xiao JC, Chen QY, Guo Y. J. Fluorine Chem. 2015; 179: 14
- 20c Hamel JD, Paquin JF. Chem. Commun. 2018; 54: 10224
- 20d Fujita T, Fuchibe K, Ichikawa J. Angew. Chem. Int. Ed. 2019; 58: 390
- 20e Yan G, Qiu K, Guo M. Org. Chem. Front. 2021; 8: 3915
- 21a Sheppard WA, Webster OW. J. Am. Chem. Soc. 1973; 95: 2695
- 21b Glinka J, Fiscus D, Rao CB, Shechter H. Tetrahedron Lett. 1987; 28: 3221
- 21c Fujimoto H, Kodama T, Yamanaka M, Tobisu M. J. Am. Chem. Soc. 2020; 142: 17323
- 21d Yu X, Meng QY, Daniliuc CG, Studer A. J. Am. Chem. Soc. 2022; 144: 7072
- 21e Yoshida T, Ohta M, Emmei T, Kodama T, Tobisu M. Angew. Chem. Int. Ed. 2023; 62: e202303657
- 22a Olah GA, Kuhn S. J. Org. Chem. 1964; 29: 2317
- 22b Olah GA, Yamato T, Hashimoto T, Shih JG, Trivedi N, Singh BP, Piteau M, Olah JA. J. Am. Chem. Soc. 1987; 109: 3708
- 22c Hirano K, Fujita K, Yorimitsu H, Shinokubo H, Oshima K. Tetrahedron Lett. 2004; 45: 2555
- 22d Hirano K, Yorimitsu H, Oshima K. Org. Lett. 2004; 6: 4873
- 23a Caputo CB, Stephan DW. Organometallics 2012; 31: 27
- 23b Dryzhakov M, Moran J. ACS Catal. 2016; 6: 3670
- 24a Henne AL, Newman MS. J. Am. Chem. Soc. 1938; 60: 1697
- 24b Burton DJ, Briney GG. J. Org. Chem. 1970; 35: 3036
- 24c Villani FJ, Mann TA, Wefer EA, Hannon J, Larca LL, Landon MJ, Spivak W, Vashi D, Tozzi S, Danko G, del Prado M, Lutz MJ. J. Med. Chem. 1975; 18: 1
- 24d Riera J, Castañer J, Carilla J, Robert A. Tetrahedron Lett. 1989; 30: 3825
- 24e Castañer J, Riera J, Carilla J, Robert A, Molins E, Miravitlles C. J. Org. Chem. 1991; 56: 103
- 24f Carilla J, Fajari L, Garcia R, Julia L, Marcos C, Riera J, Whitaker CR, Rius J, Aleman C. J. Org. Chem. 1995; 60: 2721
- 24g Ramchandani RK, Wakharkar RD, Sudalai A. Tetrahedron Lett. 1996; 37: 4063
- 25 Ooi T, Uraguchi D, Kagoshima N, Maruoka K. Tetrahedron Lett. 1997; 38: 5679
- 26a Fuchibe K, Hatta H, Oh K, Oki R, Ichikawa J. Angew. Chem. Int. Ed. 2017; 56: 5890
- 26b Meißner G, Kretschmar K, Braun T, Kemnitz E. Angew. Chem. Int. Ed. 2017; 56: 16338
- 26c Fuchibe K, Oki R, Hatta H, Ichikawa J. Chem. Eur. J. 2018; 24: 17932
- 26d Fuchibe K, Fushihara T, Ichikawa J. Org. Lett. 2020; 22: 2201
- 27a Wu J, Li X, Qi X, Duan X, Cracraft WL, Guzei IA, Liu P, Tang W. J. Am. Chem. Soc. 2019; 141: 19902
- 27b Devi L, Shukla R, Rastogi N. Org. Biomol. Chem. 2019; 17: 135
- 27c Song L, Ni D, Jia S, Pi R, Dong S, Yang F, Tang J, Liu S. Org. Lett. 2020; 22: 1846
- 28a Davies PW, Albrecht SJ. C, Assanelli G. Org. Biomol. Chem. 2009; 7: 1276
- 28b Liu Z, Sivaguru P, Zanoni G, Anderson EA, Bi X. Angew. Chem. Int. Ed. 2018; 57: 8927
- 28c Luo K, Mao S, He K, Yu X, Pan J, Lin J, Shao Z, Jin Y. ACS Catal. 2020; 10: 3733
- 29a Tayama E, Yanaki T, Iwamoto H, Hasegawa E. Eur. J. Org. Chem. 2010; 6719
- 29b Hong X, Lu L, Shen Q. Synlett 2019; 30: 1602
- 29c Li M, Sun Y, Xie Y, Yu Y, Huang F, Huang H. Chem. Commun. 2020; 56: 11050
- 30 Yan XW, Zhang Q, Wei W, Ji JX. Tetrahedron Lett. 2014; 55: 3750
- 31 Erdmann P, Leitner J, Schwarz J, Greb L. ChemPhysChem 2020; 21: 987
- 32 Lingam VS. P. R, Thomas A, Dahale DH, Rathi VE, Khairatkar-Joshi N, Mukhopadhyay I. Guanidine Derivatives as TRPC Modulators, International Patent WO 2014016766 A1, January 30, 2014
Pioneering works:
Selected reviews:
Selected reviews:
Reviews for indium-catalyzed organic reactions:
Selected papers for bioactivities of dihydrodibenzo[b,f]oxepine derivatives and -dihydrodibenzo[b,f]thiepine derivatives:
For selected reviews on C–F transformation, see:
For the insertion reaction of a carbon unit into a C–F bond, see:
For selected papers on fluoride abstraction by aluminum Lewis acids, see:
For selected recent papers, see:
For selected recent papers, see:
Selected recent papers:
Corresponding Authors
Publication History
Received: 30 April 2023
Accepted after revision: 24 July 2023
Accepted Manuscript online:
24 July 2023
Article published online:
11 September 2023
© 2023. Thieme. All rights reserved
Georg Thieme Verlag KG
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- 8 Wang F, Yi J, Nishimoto Y, Yasuda M. Synthesis 2021; 53: 4004
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- 14 Liu C, Sang S, Chen F, Yan Y, Zhang C, Huang W. J. Phys. Org. Chem. 2019; 32: e3902
- 15a Wang SH, Tu YQ, Tang M. Comprehensive Organic Synthesis, 2nd ed., Vol. 3. Knochel P. Elsevier; Amsterdam: 2014: 795
- 15b Gouygou M, Urrutigoïty M. Comprehensive Organic Synthesis, 2nd ed., Vol. 3. Knochel P. Elsevier; Amsterdam: 2014: 757
- 16 Modak A, Alegre-Requena JV, de Lescure L, Rynders KJ, Paton RS, Race NJ. J. Am. Chem. Soc. 2022; 144: 86
- 17a Masuda S, Nakajima T, Suga S. Bull. Chem. Soc. Jpn. 1983; 56: 1089
- 17b Li X, Li C, Zhang W, Lu X, Han S, Hong R. Org. Lett. 2010; 12: 1696
- 17c Tsuji Y, Richard JP. J. Phys. Org. Chem. 2016; 29: 557
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- 17f Brown HC, Kim CJ. J. Am. Chem. Soc. 1968; 90: 2082
- 18a Stopka T, Marzo L, Zurro M, Janich S, Würthwein E.-U, Daniliuc CG, Alemán J, Mancheño OG. Angew. Chem. Int. Ed. 2015; 54: 5049
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- 20a Amii H, Uneyama K. Chem. Rev. 2009; 109: 2119
- 20b Shen Q, Huang YG, Liu C, Xiao JC, Chen QY, Guo Y. J. Fluorine Chem. 2015; 179: 14
- 20c Hamel JD, Paquin JF. Chem. Commun. 2018; 54: 10224
- 20d Fujita T, Fuchibe K, Ichikawa J. Angew. Chem. Int. Ed. 2019; 58: 390
- 20e Yan G, Qiu K, Guo M. Org. Chem. Front. 2021; 8: 3915
- 21a Sheppard WA, Webster OW. J. Am. Chem. Soc. 1973; 95: 2695
- 21b Glinka J, Fiscus D, Rao CB, Shechter H. Tetrahedron Lett. 1987; 28: 3221
- 21c Fujimoto H, Kodama T, Yamanaka M, Tobisu M. J. Am. Chem. Soc. 2020; 142: 17323
- 21d Yu X, Meng QY, Daniliuc CG, Studer A. J. Am. Chem. Soc. 2022; 144: 7072
- 21e Yoshida T, Ohta M, Emmei T, Kodama T, Tobisu M. Angew. Chem. Int. Ed. 2023; 62: e202303657
- 22a Olah GA, Kuhn S. J. Org. Chem. 1964; 29: 2317
- 22b Olah GA, Yamato T, Hashimoto T, Shih JG, Trivedi N, Singh BP, Piteau M, Olah JA. J. Am. Chem. Soc. 1987; 109: 3708
- 22c Hirano K, Fujita K, Yorimitsu H, Shinokubo H, Oshima K. Tetrahedron Lett. 2004; 45: 2555
- 22d Hirano K, Yorimitsu H, Oshima K. Org. Lett. 2004; 6: 4873
- 23a Caputo CB, Stephan DW. Organometallics 2012; 31: 27
- 23b Dryzhakov M, Moran J. ACS Catal. 2016; 6: 3670
- 24a Henne AL, Newman MS. J. Am. Chem. Soc. 1938; 60: 1697
- 24b Burton DJ, Briney GG. J. Org. Chem. 1970; 35: 3036
- 24c Villani FJ, Mann TA, Wefer EA, Hannon J, Larca LL, Landon MJ, Spivak W, Vashi D, Tozzi S, Danko G, del Prado M, Lutz MJ. J. Med. Chem. 1975; 18: 1
- 24d Riera J, Castañer J, Carilla J, Robert A. Tetrahedron Lett. 1989; 30: 3825
- 24e Castañer J, Riera J, Carilla J, Robert A, Molins E, Miravitlles C. J. Org. Chem. 1991; 56: 103
- 24f Carilla J, Fajari L, Garcia R, Julia L, Marcos C, Riera J, Whitaker CR, Rius J, Aleman C. J. Org. Chem. 1995; 60: 2721
- 24g Ramchandani RK, Wakharkar RD, Sudalai A. Tetrahedron Lett. 1996; 37: 4063
- 25 Ooi T, Uraguchi D, Kagoshima N, Maruoka K. Tetrahedron Lett. 1997; 38: 5679
- 26a Fuchibe K, Hatta H, Oh K, Oki R, Ichikawa J. Angew. Chem. Int. Ed. 2017; 56: 5890
- 26b Meißner G, Kretschmar K, Braun T, Kemnitz E. Angew. Chem. Int. Ed. 2017; 56: 16338
- 26c Fuchibe K, Oki R, Hatta H, Ichikawa J. Chem. Eur. J. 2018; 24: 17932
- 26d Fuchibe K, Fushihara T, Ichikawa J. Org. Lett. 2020; 22: 2201
- 27a Wu J, Li X, Qi X, Duan X, Cracraft WL, Guzei IA, Liu P, Tang W. J. Am. Chem. Soc. 2019; 141: 19902
- 27b Devi L, Shukla R, Rastogi N. Org. Biomol. Chem. 2019; 17: 135
- 27c Song L, Ni D, Jia S, Pi R, Dong S, Yang F, Tang J, Liu S. Org. Lett. 2020; 22: 1846
- 28a Davies PW, Albrecht SJ. C, Assanelli G. Org. Biomol. Chem. 2009; 7: 1276
- 28b Liu Z, Sivaguru P, Zanoni G, Anderson EA, Bi X. Angew. Chem. Int. Ed. 2018; 57: 8927
- 28c Luo K, Mao S, He K, Yu X, Pan J, Lin J, Shao Z, Jin Y. ACS Catal. 2020; 10: 3733
- 29a Tayama E, Yanaki T, Iwamoto H, Hasegawa E. Eur. J. Org. Chem. 2010; 6719
- 29b Hong X, Lu L, Shen Q. Synlett 2019; 30: 1602
- 29c Li M, Sun Y, Xie Y, Yu Y, Huang F, Huang H. Chem. Commun. 2020; 56: 11050
- 30 Yan XW, Zhang Q, Wei W, Ji JX. Tetrahedron Lett. 2014; 55: 3750
- 31 Erdmann P, Leitner J, Schwarz J, Greb L. ChemPhysChem 2020; 21: 987
- 32 Lingam VS. P. R, Thomas A, Dahale DH, Rathi VE, Khairatkar-Joshi N, Mukhopadhyay I. Guanidine Derivatives as TRPC Modulators, International Patent WO 2014016766 A1, January 30, 2014
Pioneering works:
Selected reviews:
Selected reviews:
Reviews for indium-catalyzed organic reactions:
Selected papers for bioactivities of dihydrodibenzo[b,f]oxepine derivatives and -dihydrodibenzo[b,f]thiepine derivatives:
For selected reviews on C–F transformation, see:
For the insertion reaction of a carbon unit into a C–F bond, see:
For selected papers on fluoride abstraction by aluminum Lewis acids, see:
For selected recent papers, see:
For selected recent papers, see:
Selected recent papers:
