2-Zincoethylzincation of 2-Alkynylamines and 1-Alkynylphosphines Catalyzed by Titanium(IV) Isopropoxide and Ethylmagnesium Bromide

Abstract

Titanium(IV) isopropoxide and ethylmagnesium bromide catalyzed reaction of 2-alkynylamines with Et₂Zn, followed by deuterolysis/hydrolysis and iodinolysis, affords substituted (Z)-pent-2-en-2,5-d ₂-1-amines, (Z)-pent-2-en-1-amines (65–88%), and substituted (Z)-2,5-diiodopent-2-en-1-amines (55–63%). It is suggested that the reaction proceeds through the formation of cyclic organotitanium derivatives. The reaction between 1-alkynylphosphines and Et₂Zn in the presence of catalytic amounts of Ti(O-iPr)₄ and EtMgBr leads to trisubstituted 1-alkenylphosphine oxides with high regioselectivity and stereoselectivity.

Carbometallation is an efficient method of regio- and stereocontrolled synthesis of olefins of various structure. The most widely encountered synthetic methods for alkynes carbometallation include Zr-catalyzed Negishi methylalumination of alkynes,[1] [2] [3] carbocupration,[4,5] carbostannylation,[6] carboboration,[7] [8] and carbomagnesiation.[9] Despite the attractiveness of alkenyl organozinc intermediates due to their high functional group compatibility, carbozincation of only activated alkynes proceeds generally in satisfactory yield. Copper-catalyzed сarbozincation of alkynyl sulfoximines and alkynyl sulfones with dialkylzinc or alkylzinc halides is an example of regio- and stereoselective route to polysubstituted vinyl sulfoximines and sulfones.[10] The Cu-catalyzed carbozincation of 1-alkynyl sulfoxides with structurally different O-, N-, and Br-containing zinc halides can be used to synthesize chiral β,β-disubstituted vinylic sulfoxides with various functionalities with high syn-selectivity.[11] The efficiency of using Ni(acac)₂ for regio- and stereoselective carbometallation of a triple bond was demonstrated by carbozincation of phenyl-substituted propargyl ethers with dialkyl- and diphenylzinc.[12] However, CoCl₂-catalyzed allylzincation of substituted propargyl alcohols with allylzinc bromide proceeds with a low yield giving mixtures of regio- and stereoisomers.[13] The Rh- and Co-catalyzed carbozincation of ynamides can be used for selective synthesis of multisubstituted enamides and dienamides,[14] and also 3-arylenamides.[15] The number of known catalytic carbozincation reactions of alkynylamines is modest. For example, diastereoselective carbozincation of propargyl amine derivatives obtained from methylbenzylamine has been reported.[16] As regards P- and Se-containing alkynes, no examples of carbozincation of alkynyl phosphines or selenides are available from the literature. Meanwhile, it is known that 1-alkynylphosphines, 1-alkynylphosphonates, propargylamines, 1-alkynyl selenides, and 1-alkynyl sulfides are efficient substrates for the preparation of zirconacyclopentenes[17] [18] [19] [20] and aluminacyclopentenes.[21] [22] [23] [24] Regarding 2-zincoethylzincation, only one case of the preparation of organozinc derivative in 63% yield only after 4 days using the Ti-Mg-catalyzed reaction of 5-decyne with Et₂Zn has been reported in the literature.[25] However, this reaction is a unique example of carbozincation of the triple carbon–carbon bond with Et₂Zn using oxidative coupling of ethylene and 5-decyne on titanium(II) in catalytic cycle. Evidently, the full-scale application of the synthetic potential of this reaction is impossible without systematic research of its scope and mechanism. Currently, nothing is known about the behaviors of N-, P-, O-, S-, and Se-containing alkynes and alkenes in this reaction. In this paper, we report our results on the selective 2-zincoethylzincation of heteroatom-substituted alkynes such as 2-alkynylamines and 1-alkynylphosphines. This work demonstrates that α- or β-heteroatom-substituted alkynes react much more promptly than internal aliphatic alkynes, and thus enhances significantly the synthetic scope of the transformation by disclosing an efficient access to some heteroatom-functionalized alkenes with control of the double-bond geometry. The study represents an improvement over previous works on Zr-catalyzed cycloalumination of propargylamines[21] and alkynylphosphines[22] because the current catalytic system consisting of Et₂Zn, Ti(O-iPr)₄, and EtMgBr is more practical and less costly. Moreover, the dizincated species offer more potential for subsequent functionalization than the dialuminated species.

We found that 2-alkynylamines 1 react with 2.5 equiv of Et₂Zn (1 M in hexanes) in the presence of 10 mol% Ti(O-iPr)₄, (0.5 M in hexanes) and 20 mol% EtMgBr (2.5 M in Et₂O) in diethyl ether at room temperature for 18 hours to give, after deuterolysis, hydrolysis, or iodinolysis substituted allylamines 3–5 (Scheme [1]).[26]

The structures of the resulting substituted allylamines were established using 1D and 2D NMR spectroscopy for the their deuterolysis 3a and hydrolysis 4a–g products. In the ¹Н NMR spectra of compounds 4a–g, the doublet for the methylene group of the N,N-dimethylaminomethyl moiety unambiguously proves the formation of regioisomer 4. The NOESY spectrum of compound 4a clearly shows two cross-peaks of the triplet for the vinylic proton with the triplet for the methyl proton of the ethyl group, and also with the quadruplet for the methylene group of the ethyl substituent, indicating the Z-configuration of the formed substituted allylamine. The 2-zincoethylzincation reaction is equally regio- and stereoselective for 1-(3-cyclopropylprop-2-yn-1-yl)piperidine (1e), 1-(hept-2-yn-1-yl)piperidine (1f), and 4-(hept-2-yn-1-yl)morpholine (1g) as well. The regio- and stereoselectivity of this reaction coincide with those that we observed earlier for the cycloalumination of 2-alkynylamines.[20] We carried out the iodinolysis of the organometallic intermediates formed during the carbozincation of 2-alkynylamines. Thus, the reaction of organozinc intermediates 2 obtained by 2-zincoethylzincation of 2-alkynylamines 1b,c,f,g with 5.3 equiv of I₂proceeds selectively to afford Z-configured diiodo-substituted allylamines 5 b,c,f,g (55–63%). It is also noteworthy that diethyl ether is the solvent of choice for 2-zincoethylzincation of 2-alkynylamines, whereas tetrahydrofuran, dimethoxyethane, and 1,4-dioxane completely inhibit the transformation of 2-alkynylamines.

Previously, we have shown that Zr-catalyzed cycloalumination of α,ω-bis(aminomethyl)alkadiynes with Et₃Al results in the selective formation of a bis-alkylidene cyclohexane derivative.[21] A similar formation of bis-alkylidene-substituted cyclohexane was also observed upon the carboalumination of trimethyl(oct-7-en-1-yn-1-yl)silane.[27] Similarly, the reaction of N,N,N′,N′-tetramethyldeca-2,8-diyne-1,10-diamine with 2.5 equiv of Et₂Zn in the presence of 10 mol% Ti(O-iPr)₄and 20 mol% EtMgBr carried out in diethyl ether at room temperature for 18 hours and followed by deuterolysis or hydrolysis affords bis-alkylidene cyclohexane 6 and 7 derivative (Scheme [2]).

According to Scheme [2] (b) , Ti(O-iPr)₄ reacts with EtMgBr with fast ligand exchange giving (O-iPr)₂TiEt₂, which forms the (O-iPr)₂Ti–ethylene complex. The insertion of one of the triple bonds of tetramethyldeca-2,8-diyne-1,10-diamine into the Ti–C bond of this complex results in ethylene displacement from the titanium coordination sphere and coupling of two alkyne moieties to give titanacyclopentadiene, which is then transmetalated in the catalytic cycle to be converted, after subsequent deuterolysis (or hydrolysis), into the target bis-alkylidene cyclohexane derivative 6 and 7. The NOESY spectrum of compound 7 shows coupling between the methylene group of the N,N-dimethylaminomethyl moiety and the α-methylene group of the cyclohexane moiety, thus indicating E-configuration of the double bonds. The cross-peak between the triplet for the proton at the double bond and the doublet for the N-methylene group in the COSY spectrum of hydrolysis product 7 attests to the geminal positions of the hydrogen atom andN,N-dimethylaminomethyl group at a double-bond carbon atom.

Similar results were obtained for 2-alkynylamines 8 prepared from phenylacetylene: N,N-dimethyl-3-phenylprop-2-yn-1-amine and 1-(3-phenylprop-2-yn-1-yl)piperidine (Scheme [3]). However, unlike the reaction of alkyl-substituted propargylamines, in this case, the reaction was not regioselective and gave a mixture of regioisomers 9, 10 and 9′,10′. The Overhauser effects between the methylene-group protons Н₂С-1 (δ = 2.83 ppm) and the phenyl-group proton at С-13 (δ = 7.14 ppm) observed in the NOESY spectrum of regioisomer 9a are indicative of cis-arrangement of the aromatic and dimethylaminomethyl groups relative to the double bond (Scheme [3]). Z-Configuration of the double bond in 9′a is evidenced by the cross-peak between the methylene-group protons Н₂С-1 (δ = 3.07 ppm) and the phenyl-group proton at С-13. Coupling between the protons at С-4 (δ = 2.38 ppm) and the С-8 carbon (δ = 141.16 ppm) in 10a points to the geminal positions of the phenyl and ethyl groups at a double-bond carbon. Comparison of the ¹Н NMR and ¹³C NMR signal intensities for compounds 10a and 10′a leads to the conclusion that compound 10a is present in a 1.5-fold greater amount in the isomer mixture. Presumably, agostic interaction between the titanium atom and the ortho-hydrogen atom of the phenyl group may be one of the causes for the observed lack of regioselectivity in the transformation of aryl-substituted propargylamines 8.[28]

Thus, the presence of the amine function in the molecule of alkyne does not preclude the reaction of Ti-Mg-catalyzed 2-zincoethylzincation. Meanwhile, phosphorus is a close electronic analogue of nitrogen. Previously, we have shown that 1-alkynylphosphines are useful substrates for the synthesis of 1-alkenylphosphines by Zr-catalyzed cycloalumination with Et₃Al.[22] Tertiary phosphines and their oxides are widely used ligands in organometallic and coordination chemistry.[29] In order to develop new methods for the synthesis of various phosphorus oxides, we studied the Ti-Mg-catalyzed reaction of 1-alkynylphosphines with Et₂Zn. Earlier, Takahashi investigated the pair-selective coupling of (hex-1-yn-1-yl)diphenylphosphine with zirconocene–ethylene complex, which was generated in situ from Cp₂ZrEt₂.[30] The (Z)-(2-ethylhex-1-en-1-yl)diphenylphosphine was formed in 96% GC yield with perfect regio- and stereoselectivity.[17] We found that the reaction of 1-alkynylphosphines 11 with 2.5 equiv of Et₂Zn (1 M in hexanes) in the presence of 10 mol% Ti(O-iPr)₄, (0.5 M in hexanes) and 20 mol% EtMgBr (2.5 M in Et₂O) carried out in diethyl ether at room temperature for 18 hours, followed by deuterolysis (or hydrolysis) and then oxidation with H₂O₂, as well as then sulfonation with S₈furnishes Z-configured 1-alkenylphosphine oxides 12b–e, 13a,e and alkenyl sulfides 14a,b (Scheme [4]). Since 1-alkenylphosphines are readily oxidized in air to give phosphorus oxides,[21] we carried out the oxidation of deuterated (or hydrogenated) alkenylphosphines with H₂O₂to 1-alkenylphosphine oxides, which were readily purified by column chromatography. The structure of the 1-alkenylphosphine oxides was established using 1D and 2D NMR spectroscopy for the products of deuterolysis 12b–e and hydrolysis 13a,e. All experimental data for compounds 12b–e and 13a,eare in good agreement with the ¹H NMR, ¹³C NMR, and ³¹P NMR characteristics reported previously for structurally identical 1-alkenylphosphine oxides.[22] Note that in the case of 1- alkynylphosphines, the presence of a phenyl substituent at the triple bond does not change the reaction regiochemistry, unlike the case of propargylamines. The 2-zincoethylzincation of diphenyl(phenylethynyl)phosphine proceeds regioselectively to give a single regioisomer 12e (13e) with geminal positions of the phenyl and ethyl substituents at a double-bond carbon atom.

This study demonstrates that the presence of the amine or phosphine functional groups in the molecule of alkyne does not prevent but rather facilitates the 2-zincoethylzincation reaction. The strategy we developed opens up the way to the synthesis of heterofunctional alkenes of various structure via catalytic 2-zincoethylzincation of functionally substituted alkynes. In addition, the disclosed regio- and stereoselective transformation of 1-alkynylphosphines and 2-alkynylamines opens up new prospects for the synthesis of various polyfunctional compounds using a broad range of transformations of the functionally substituted organozinc intermediates formed in situ. These and other goals will be pursued in our subsequent studies.

• References and Notes

• 1 Van Horn DE, Negishi E-i. J. Am. Chem. Soc. 1978; 100: 2252
  CrossrefSearch in Google Scholar
• 2 Negishi E.-I, Van Horn DE, Yoshida T. J. Am. Chem. Soc. 1985; 107: 6639
  CrossrefSearch in Google Scholar
• 3 Negishi E.-I. Pure Appl. Chem. 1981; 53: 2333
  CrossrefSearch in Google Scholar
• 4 Normant JF, Bourgain M. Tetrahedron Lett. 1971; 2583
• 5 Normant JF. J. Organomet. Chem. Libr. 1976; 1: 2199
  Search in Google Scholar
• 6 Shirakawa E, Yamasaki K, Yoshida H, Hiyama T. J. Am. Chem. Soc. 1999; 121: 10221
  CrossrefSearch in Google Scholar
• 7 Suginome M, Shirakura M, Yamamoto A. J. Am. Chem. Soc. 2006; 128: 14438
  CrossrefPubMedSearch in Google Scholar
• 8 Daini M, Suginome M. Chem. Commun. 2008; 5224
  PubMed
• 9 Shirakawa E, Yamagami T, Kimura T, Yamaguchi S, Hayashi T. J. Am. Chem. Soc. 2005; 127: 17164
  CrossrefPubMedSearch in Google Scholar
• 10 Sklute G, Bolm C, Marek I. Org. Lett. 2007; 9: 1259
  CrossrefPubMedSearch in Google Scholar
• 11 Maezaki N, Sawamoto H, Yoshigami R, Suzuki T, Tanaka T. Org. Lett. 2003; 5: 1345
  CrossrefPubMedSearch in Google Scholar
• 12 Stüdemann T, Ibrahim-Ouali M, Knochel P. Tetrahedron 1998; 54: 1299
  CrossrefSearch in Google Scholar
• 13 Yasui H, Nishikawa T, Yorimitsu H, Oshima K. Bull. Chem. Soc. Jpn. 2006; 79: 1271
  CrossrefSearch in Google Scholar
• 14 Gourdet B, Lam HW. J. Am. Chem. Soc. 2009; 131: 3802
  CrossrefPubMedSearch in Google Scholar
• 15 Sallio R, Corpet M, Habert L, Durandetti M, Gosmini C, Gillaizeau I. J. Org. Chem. 2017; 82: 1254
  CrossrefPubMedSearch in Google Scholar
• 16 Rezaei H, Marek I, Normant JF. Tetrahedron 2001; 57: 2477
  CrossrefSearch in Google Scholar
• 17 Xi Z, Zhang W, Takahashi T. Tetrahedron Lett. 2004; 45: 2427
  CrossrefSearch in Google Scholar
• 18 Ben-Valid S, Quntar AA. A, Srebnik M. J. Org. Chem. 2005; 70: 3554
  CrossrefPubMedSearch in Google Scholar
• 19 Negishi E. Dalton Trans. 2005; 827
  PubMed
• 20 Al-Aziz Al-QuntarA, Srebnik M. J. Organomet. Chem. 2005; 690: 2504
  CrossrefSearch in Google Scholar
• 21 Ramazanov IR, Kadikova RN, Dzhemilev UM. Russ. Chem. Bull. 2011; 60: 99
  CrossrefSearch in Google Scholar
• 22 Ramazanov IR, Kadikova RN, Saitova ZR, Dzhemilev UM. Asian J. Org. Chem. 2015; 4: 1301
  CrossrefSearch in Google Scholar
• 23 Kadikova RN, Ramazanov IR, Vyatkin AV, Dzhemilev UM. Synthesis 2017; 49: 4523
  Thieme ConnectSearch in Google Scholar
• 24 Kadikova RN, Ramazanov IR, Vyatkin AV, Dzhemilev UM. Synlett 2018; 29: 1773
  Thieme ConnectSearch in Google Scholar
• 25 Montchamp J.-L, Negishi E.-i. J. Am. Chem. Soc. 1998; 120: 5345
  CrossrefSearch in Google Scholar
• 26 To a solution of N,N-dimethylhept-2-yn-1-amine (278 mg, 2 mmol) and Et₂Zn (1 M in hexanes, 5 mL, 5 mmol) in Et₂O (6 mL) was added Ti(O-iPr)₄ (0.5 M in hexanes, 0.4 mL, 0.2 mmol). Ethylmagnesium bromide (2.5 M in Et₂O, 0.16 mL, 0.4 mmol) was then added, and the reaction mixture rapidly turned black. After 18 h at 23 °C, the reaction mixture was diluted with Et₂O (5 mL), and 25 wt% NaOH (3 mL) was added dropwise while the reaction flask was cooled in an ice bath. The aqueous layer was extracted with Et₂O (3 × 5 mL). The combined organic layers were washed with brine (10 mL) and dried over anhydrous CaCl₂. The reaction mixture was filtered through a filter paper and concentrated in vacuo to give crude product as a yellow oil. The residue was distilled through a micro column at 10 mmHg to give (Z)-3-ethyl-N,N-dimethylhept-2-en-1-amine (226 mg, 67%) as a colorless oil; bp 86–88 °С (10 mmHg). ¹H NMR (400 MHz, CDCl₃): δ = 0.92 (t, J= 6.6 Hz, 3 Н, С(11)Н₃), 1.02 (t, J= 7.4 Hz, 3 Н, С(5)Н₃), 1.25–1.40 (m, 4 Н, С(9,10)Н₂), 2.00–2.10 (m, 2 Н, С(4)Н₂), 2.10–2.35 (m, 2 Н, С(8)Н₂), 2.24 (s, 6 Н, С(6,7)Н₃), 2.91 (d, J= 6.7 Hz, 2 Н, С(1)Н₂), 5.23 (t, J= 6.6 Hz, 1 Н, С(2)Н₁).¹³C NMR (100 MHz, CDCl₃): δ = 12.73 (C(5)), 14.03 (C(11)), 22.85 (C(10)), 29.57 and 30.31 and 30.72 (C(4,8,9)), 45.24 (2 C(6,7)), 56.83 (C(1)), 120.47 (C(2)), 144.38 (C(3)). MS (EI): m/z,% = 169 (15) [M⁺], 140 (9), 124 (14), 112 (21), 95 (100), 82 (32), 58 (49), 46 (48). Anal. Calcd for C₁₁H₂₃N (%): C, 78.03; H, 13.69; N, 8.27. Found: C, 78.1; H, 13.7; N, 8.1.
• 27 Negishi E.-I, Montchamp J.-L, Anastasia L, Elizarov A, Choueiry D. Tetrahedron Lett. 1998; 39: 2503
  CrossrefSearch in Google Scholar
• 28 Brookhart M, Green ML. H, Gerard P. Proc. Natl. Acad. Sci. U.S.A. 2007; 104: 6909
  Search in Google Scholar
• 29 Bertrand G. Chem. Rev. 1994; 94: 1161
  CrossrefSearch in Google Scholar
• 30a Takahashi T, Kageyama M, Denisov V, Hara R, Negishi E. Tetrahedron Lett. 1993; 34: 687
  CrossrefSearch in Google Scholar
• 30b Xi Z, Hara R, Takahashi T. J. Org. Chem. 1995; 60: 4444
  CrossrefSearch in Google Scholar
• 30c Takahashi T, Xi C, Xi Z, Kageyama M, Fischer R, Nakajima K, Negishi E. J. Org. Chem. 1998; 63: 6802
  CrossrefPubMedSearch in Google Scholar

• References and Notes

• 1 Van Horn DE, Negishi E-i. J. Am. Chem. Soc. 1978; 100: 2252
  CrossrefSearch in Google Scholar
• 2 Negishi E.-I, Van Horn DE, Yoshida T. J. Am. Chem. Soc. 1985; 107: 6639
  CrossrefSearch in Google Scholar
• 3 Negishi E.-I. Pure Appl. Chem. 1981; 53: 2333
  CrossrefSearch in Google Scholar
• 4 Normant JF, Bourgain M. Tetrahedron Lett. 1971; 2583
• 5 Normant JF. J. Organomet. Chem. Libr. 1976; 1: 2199
  Search in Google Scholar
• 6 Shirakawa E, Yamasaki K, Yoshida H, Hiyama T. J. Am. Chem. Soc. 1999; 121: 10221
  CrossrefSearch in Google Scholar
• 7 Suginome M, Shirakura M, Yamamoto A. J. Am. Chem. Soc. 2006; 128: 14438
  CrossrefPubMedSearch in Google Scholar
• 8 Daini M, Suginome M. Chem. Commun. 2008; 5224
  PubMed
• 9 Shirakawa E, Yamagami T, Kimura T, Yamaguchi S, Hayashi T. J. Am. Chem. Soc. 2005; 127: 17164
  CrossrefPubMedSearch in Google Scholar
• 10 Sklute G, Bolm C, Marek I. Org. Lett. 2007; 9: 1259
  CrossrefPubMedSearch in Google Scholar
• 11 Maezaki N, Sawamoto H, Yoshigami R, Suzuki T, Tanaka T. Org. Lett. 2003; 5: 1345
  CrossrefPubMedSearch in Google Scholar
• 12 Stüdemann T, Ibrahim-Ouali M, Knochel P. Tetrahedron 1998; 54: 1299
  CrossrefSearch in Google Scholar
• 13 Yasui H, Nishikawa T, Yorimitsu H, Oshima K. Bull. Chem. Soc. Jpn. 2006; 79: 1271
  CrossrefSearch in Google Scholar
• 14 Gourdet B, Lam HW. J. Am. Chem. Soc. 2009; 131: 3802
  CrossrefPubMedSearch in Google Scholar
• 15 Sallio R, Corpet M, Habert L, Durandetti M, Gosmini C, Gillaizeau I. J. Org. Chem. 2017; 82: 1254
  CrossrefPubMedSearch in Google Scholar
• 16 Rezaei H, Marek I, Normant JF. Tetrahedron 2001; 57: 2477
  CrossrefSearch in Google Scholar
• 17 Xi Z, Zhang W, Takahashi T. Tetrahedron Lett. 2004; 45: 2427
  CrossrefSearch in Google Scholar
• 18 Ben-Valid S, Quntar AA. A, Srebnik M. J. Org. Chem. 2005; 70: 3554
  CrossrefPubMedSearch in Google Scholar
• 19 Negishi E. Dalton Trans. 2005; 827
  PubMed
• 20 Al-Aziz Al-QuntarA, Srebnik M. J. Organomet. Chem. 2005; 690: 2504
  CrossrefSearch in Google Scholar
• 21 Ramazanov IR, Kadikova RN, Dzhemilev UM. Russ. Chem. Bull. 2011; 60: 99
  CrossrefSearch in Google Scholar
• 22 Ramazanov IR, Kadikova RN, Saitova ZR, Dzhemilev UM. Asian J. Org. Chem. 2015; 4: 1301
  CrossrefSearch in Google Scholar
• 23 Kadikova RN, Ramazanov IR, Vyatkin AV, Dzhemilev UM. Synthesis 2017; 49: 4523
  Thieme ConnectSearch in Google Scholar
• 24 Kadikova RN, Ramazanov IR, Vyatkin AV, Dzhemilev UM. Synlett 2018; 29: 1773
  Thieme ConnectSearch in Google Scholar
• 25 Montchamp J.-L, Negishi E.-i. J. Am. Chem. Soc. 1998; 120: 5345
  CrossrefSearch in Google Scholar
• 26 To a solution of N,N-dimethylhept-2-yn-1-amine (278 mg, 2 mmol) and Et₂Zn (1 M in hexanes, 5 mL, 5 mmol) in Et₂O (6 mL) was added Ti(O-iPr)₄ (0.5 M in hexanes, 0.4 mL, 0.2 mmol). Ethylmagnesium bromide (2.5 M in Et₂O, 0.16 mL, 0.4 mmol) was then added, and the reaction mixture rapidly turned black. After 18 h at 23 °C, the reaction mixture was diluted with Et₂O (5 mL), and 25 wt% NaOH (3 mL) was added dropwise while the reaction flask was cooled in an ice bath. The aqueous layer was extracted with Et₂O (3 × 5 mL). The combined organic layers were washed with brine (10 mL) and dried over anhydrous CaCl₂. The reaction mixture was filtered through a filter paper and concentrated in vacuo to give crude product as a yellow oil. The residue was distilled through a micro column at 10 mmHg to give (Z)-3-ethyl-N,N-dimethylhept-2-en-1-amine (226 mg, 67%) as a colorless oil; bp 86–88 °С (10 mmHg). ¹H NMR (400 MHz, CDCl₃): δ = 0.92 (t, J= 6.6 Hz, 3 Н, С(11)Н₃), 1.02 (t, J= 7.4 Hz, 3 Н, С(5)Н₃), 1.25–1.40 (m, 4 Н, С(9,10)Н₂), 2.00–2.10 (m, 2 Н, С(4)Н₂), 2.10–2.35 (m, 2 Н, С(8)Н₂), 2.24 (s, 6 Н, С(6,7)Н₃), 2.91 (d, J= 6.7 Hz, 2 Н, С(1)Н₂), 5.23 (t, J= 6.6 Hz, 1 Н, С(2)Н₁).¹³C NMR (100 MHz, CDCl₃): δ = 12.73 (C(5)), 14.03 (C(11)), 22.85 (C(10)), 29.57 and 30.31 and 30.72 (C(4,8,9)), 45.24 (2 C(6,7)), 56.83 (C(1)), 120.47 (C(2)), 144.38 (C(3)). MS (EI): m/z,% = 169 (15) [M⁺], 140 (9), 124 (14), 112 (21), 95 (100), 82 (32), 58 (49), 46 (48). Anal. Calcd for C₁₁H₂₃N (%): C, 78.03; H, 13.69; N, 8.27. Found: C, 78.1; H, 13.7; N, 8.1.
• 27 Negishi E.-I, Montchamp J.-L, Anastasia L, Elizarov A, Choueiry D. Tetrahedron Lett. 1998; 39: 2503
  CrossrefSearch in Google Scholar
• 28 Brookhart M, Green ML. H, Gerard P. Proc. Natl. Acad. Sci. U.S.A. 2007; 104: 6909
  Search in Google Scholar
• 29 Bertrand G. Chem. Rev. 1994; 94: 1161
  CrossrefSearch in Google Scholar
• 30a Takahashi T, Kageyama M, Denisov V, Hara R, Negishi E. Tetrahedron Lett. 1993; 34: 687
  CrossrefSearch in Google Scholar
• 30b Xi Z, Hara R, Takahashi T. J. Org. Chem. 1995; 60: 4444
  CrossrefSearch in Google Scholar
• 30c Takahashi T, Xi C, Xi Z, Kageyama M, Fischer R, Nakajima K, Negishi E. J. Org. Chem. 1998; 63: 6802
  CrossrefPubMedSearch in Google Scholar

• Supplementary Material