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Synlett 2009(16): 2669-2672  
DOI: 10.1055/s-0029-1217977
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

An Efficient Catalytic Sulfonyloxylactonization of Alkenoic Acids Using Hypervalent Iodine(III) Reagent

Jie Yan*, Hong Wang, Zhenping Yang, Yan He
College of Chemical Engineering and Materials Sciences, Zhejiang University of Technology, Hangzhou 310032, Zhejiang, P. R. of China
Fax: +86(571)88320238; e-Mail: jieyan87@zjut.edu.cn;

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Publication History

Received 22 June 2009
Publication Date:
10 September 2009 (online)

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Abstract

A novel and efficient catalytic method for sulfonyloxylactonization of alkenoic acids is reported. (Diacetoxyiodo)benzene could be used as a recyclable catalyst in combination with m-chloroperbenzoic acid as an oxidant in the presence of sulfonic acid to effect the cyclization of various alkenoic acids in CH2Cl2 at room temperature, giving sulfonyloxylactones in good yields.

Key words

sulfonyloxylactonization - hypervalent iodine reagent - catalytic cyclization

Organic hypervalent iodine reagents have found broad application in organic chemistry and frequently used in synthesis due to their chemical properties and reactivity similarities to those of Hg(II), Tl(III), and Pb(IV), but without the toxic and environmental problems of these heavy-metal congeners. [¹] They are usually used as mild oxidants, [²] and also as electrophilic reagents, with them various cyclizations of unsaturated systems have been carried out. [³] Koser and co-workers first reported the tosyl­oxylactonization of alkenoic acids with the hypervalent iodine reagent, [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser’s reagent), and the ability of HTIB to introduce the tosylate ligand into alkenoic acids received much attention. [³b] Recently, the catalytic utilization of hypervalent iodine reagents is increasing in importance, with growing interest in the development of environmentally benign synthetic transformations. [4] Kita and co-workers used catalytic amounts of hypervalent iodine(III) reagents and meta-chloroperbenzoic acid (MCPBA) as an oxidant in the spirocyclization of phenol and amide derivatives. [5] Ochiai and co-workers reported the α-acetoxylation of ketones with the combination of a catalytic amount of an aryl iodide and MCPBA as the oxidant. [6] In these catalytic reactions, a catalytic amount of an iodine-containing molecule together with a stoichiometric oxidant were used. The oxidant generated the hypervalent iodine reagent in situ, and after the oxidative transformation, the reduced iodine-containing molecule was re-oxidized. PhI-catalyzed α-tosyloxylation of ketones with MCPBA and p-­tosylic acid (TsOH) has also received considerable attention. [7] However, the catalytic sulfonyloxylactonization of alkenoic acids has not been reported before.

In order to extend the scope of catalytic use of organo­iodines(III) for organic synthesis, we have investigated a series of cyclizations of alkenoic acids using catalytic amounts of hypervalent iodine(III) reagents and MCPBA as a stoichiometric chemical oxidant. Herein, we wish to report the first example of the catalytic sulfonyloxylactonization of alkenoic acids.

Table 1 Optimization of the Tosyloxylactonization of 4-Pentenoic Acid

Entry DIB (equiv) MCPBA (equiv) TsOH (equiv)a Solvent Time (h) Yield (%)b
 1 0.1 1 1 CH2Cl2  1 45
 2 0.1 1 1 CH2Cl2  2 53
 3 0.1 1 1 CH2Cl2  4 69
 4 0.1 1 1 CH2Cl2   8 72
 5 0.1 1 1 CH2Cl2 16 75
 6 0.1 1 1 CH2Cl2 24 82
 7 0.1 1 1 CH2Cl2 92 84
 8 0.1 2 2 CH2Cl2 24 84
 9 0.05 1 1 CH2Cl2 24 63
10 0.02 1 1 CH2Cl2 24 51
11 0.1 1 1 MeCN 24 62
12 0.1 1 1 MeCN 24 50
13 0.1 1 1 THF 24 54
14 0.1c 1 1 CH2Cl2 24 81
15 0 1 1 CH2Cl2 24  0
a Ts, 4-MeC6H4SO2. b Isolate yields.
c PhI was used instead of DIB.

Initially, we examined the tosyloxylactonization of 4-pentenoic acid (1a) with 0.1 equivalents of (diacetoxyiodo)benzene (DIB) in the presence of the equal equivalent of TsOH (2a) and MCPBA in CH2Cl2 at room temperature. The reaction proceeded smoothly and gave the desired product of 5-tosyloxy-4-pentanolactone (3a) in 45% yield in 1 hour (Table  [¹] , entry 1). Then, the reaction conditions were optimized. As the reaction time was prolonged, the yield of 3a was increased (entries 1-7) and 24 hours was the best suitable reaction time. The amount of catalyst DIB was influential (entries 9 and 10), and 0.1 equivalent was the best choice. As a suitable solvent, CH2Cl2 was the most preferred (entries 6, 11-13). When PhI was used instead of DIB, nearly the same result was obtained (entry 14). In the absence of DIB, the sulfonyloxylactonization was not observed (entry 15). Other co-oxidants such as sodium perborate and Oxone® [c1] were also not successful.

Under the optimized reaction conditions, we investigated the catalytic sulfonylactonization of equal equivalent al­kenoic acids 1, TsOH 2a or (+)-10-camphorsulfonic acid (2b) and MCPBA with 0.1 equivalents DIB (Scheme  [¹] ), and the results are summarized in Table  [²] . [8] It was found that good yields of 5-sulfonyloxy-4-pentanolactones were obtained for a series of 4-pentenoic acids (entries 1-3, 7-10). Similar treatment of 5-hexenoic acid provided 6-sulfonyloxy-5-hexanolactones in moderate yields (entries 4 and 11). When 3-butenoic acid and trans-3-hexenoic acids were treated with 2a under the same reaction conditions, only the unsaturated lactones were given (entries 5 and 6), but not the desired sulfonylactons. It was revealed by ¹H NMR spectroscopy that the desired 3-sulfonyloxy-4-butanolactones were first formed, but then further transformed into the unsaturated lactones during workup procedure.

Scheme 1 Hypervalent iodine(III) catalyzed sulfonylactonization of alkenoic acids

Table 2 Hypervalent Iodine(III) Catalyzed Sulfonylactonization of Alkenoic Acids (continued)
Entry Alkenoic acid 1 Sulfonic acid 2 Sulfonyloxylactone 3 a Yield (%)b
 1 H2C=CH(CH2)2CO2H 1a TsOH 2a

3a 		82
 2

1b 		2a

3b 		83
 3

1c 		2a

3c 		83
 4 H2C=CH(CH2)3CO2H 1d 2a

3d 		52
 5 H2C=CHCH2CO2H 1e 2a

3e 		45
 6

1f 		2a

3f 		30
 7 1a (+)-10-camphorsulfonic acid
2b

3g 		83
 8 1b 2b

3h 		76
 9 1c 2b

3i 		75
10

1g 		2b

3j 		87
11 1d 2b

3k 		57
a Ts, 4-MeC6H4SO2; Cs, (+)-10-camphorylsulfonyl.
b Isolated yield.

In 1988, Koser and co-workers reported another lactonizaton using the hypervalent iodine reagent, ­{hydroxy[(bis(phenyloxy)phosphoryl)oxy]iodo}benzene, and they found when 2-methyl-4-pentenoic acid (1b) was treated with the hypervalent iodine reagent, the products were a mixture of diastereomers, with a ratio varied from 1.2 to 1.4:1. [³c] In our reaction protocol, we also found when 1b was used the corresponding 5-sulfonyloxy-4-pentanolactones were obtained as a mixture of diastereo­mers, with a ratio varied from 2.7:1 for p-tosylic acid to 2.4:1 for camphorsulfonic acid, respectively, as determined by examination of the ¹H NMR spectra of sulfonylactones. When 3-methyl-4-pentenoic acid (1c) was reacted under the same conditions, the ratios of the mixture of diastereomers were 1.7:1 and 2.0:1 for p-tosylic acid and camphorsulfonic acid, respectively, which were somewhat lower as compared to compound 1b.

A proposed mechanism for the catalytic cycle of sulfonylactonization is depicted in Scheme  [²] , [³b] which included an electrophilic addition of hypervalent iodine reagent to the double bond, and then an intramolecular nucleophilic cyclization happened, followed by another nucleophilic sulfonyloxylation. The reduced byproduct of PhI was then regenerated into hypervalent iodine reagent by the oxidation of MCPBA and used in the next reaction cycle.

Scheme 2 The possible catalytic cycle for the hypervalent io­dine(III) catalyzed sulfonylactonization of alkenoic acids

In conclusion, we have successfully developed an efficient catalytic sulfonyloxylactonization of alkenoic acids using hypervalent iodine catalyst DIB and MCPBA in presence of sulfonic acids. This new protocol has some advantages such as mild reaction conditions, simple procedure, and good product yields. Furthermore, the scope of catalytic use of hypervalent iodine reagents in organic synthesis could be extended. Further investigation of the cyclizations of alkenoic acids using catalytic amounts of hypervalent iodine(III) reagents and MCPBA as a stoi­chiometric chemical oxidant will be reported in due course.

Supporting Information for this article is available online at http://www.thieme-connect.com.accesdistant.sorbonne-universite.fr/ejournals/toc/synlett.

Acknowledgment

Financial support from the Natural Science Foundation of China (Project 20672100) and Zhejiang Province Natural Science Foundation of China (Project Y4080068) are greatly appreciated.

8

Typical Procedure for the Catalytic Sulfonyloxylactonization of Alkenoic Acids
To CH2Cl2 (2 mL), alkenoic acid 1 (0.3 mmol),(diacetoxy-iodo)benzene (0.03 mmol), MCPBA (75%, 0.3 mmol) and sulfonic acid 2 (0.3 mmol) were added. The mixture was stirred at r.t. for 24 hours and then H2O (5 mL), sat. aq Na2S2O3 (2 mL), and sat. aq Na2CO3 (2 mL) were added.
The mixture was extracted with CH2Cl2 (2 × 5 mL), the combined organic layer was washed with brine, dried over anhyd MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by preparative TLC on a silica gel using (hexane-EtOAc, 2:1) as eluent to give sulfonyloxylacton 3 in good yields.

8

Typical Procedure for the Catalytic Sulfonyloxylactonization of Alkenoic Acids
To CH2Cl2 (2 mL), alkenoic acid 1 (0.3 mmol),(diacetoxy-iodo)benzene (0.03 mmol), MCPBA (75%, 0.3 mmol) and sulfonic acid 2 (0.3 mmol) were added. The mixture was stirred at r.t. for 24 hours and then H2O (5 mL), sat. aq Na2S2O3 (2 mL), and sat. aq Na2CO3 (2 mL) were added.
The mixture was extracted with CH2Cl2 (2 × 5 mL), the combined organic layer was washed with brine, dried over anhyd MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by preparative TLC on a silica gel using (hexane-EtOAc, 2:1) as eluent to give sulfonyloxylacton 3 in good yields.

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Scheme 1 Hypervalent iodine(III) catalyzed sulfonylactonization of alkenoic acids

Scheme 2 The possible catalytic cycle for the hypervalent io­dine(III) catalyzed sulfonylactonization of alkenoic acids