Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex: Structural determination of the asymmetric catalyst

T. Nemoto; T. Ohshima; K. Yamaguchi; M. Shibasaki

doi:10.1021/ja004201e

Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex: Structural determination of the asymmetric catalyst

T. Nemoto, T. Ohshima, K. Yamaguchi, M. Shibasaki

Research output: Contribution to journal › Article › peer-review

152 Citations (Scopus)

Abstract

The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph₃As=O complex generated from La(O-i-Pr)₃, BINOL, and Ph₃As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)₂(Ph₃As=O)₂ (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)₃, BINOL, and Ph₃As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph₃As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)₃ for accelerating the epoxidations while maintaining high ee's is discussed.

Original language	English
Pages (from-to)	2725-2732
Number of pages	8
Journal	Journal of the American Chemical Society
Volume	123
Issue number	12
DOIs	https://doi.org/10.1021/ja004201e
Publication status	Published - Oct 10 2001
Externally published	Yes

All Science Journal Classification (ASJC) codes

Catalysis
Chemistry(all)
Biochemistry
Colloid and Surface Chemistry

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@article{55bba110bcac4b6990e344b0ebf1d40b,

title = "Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex: Structural determination of the asymmetric catalyst",

abstract = "The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph3As=O complex generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)2(Ph3As=O)2 (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph3As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)3 for accelerating the epoxidations while maintaining high ee's is discussed.",

author = "T. Nemoto and T. Ohshima and K. Yamaguchi and M. Shibasaki",

year = "2001",

month = oct,

day = "10",

doi = "10.1021/ja004201e",

language = "English",

volume = "123",

pages = "2725--2732",

journal = "Journal of the American Chemical Society",

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T1 - Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex

T2 - Structural determination of the asymmetric catalyst

AU - Nemoto, T.

AU - Ohshima, T.

AU - Yamaguchi, K.

AU - Shibasaki, M.

PY - 2001/10/10

Y1 - 2001/10/10

N2 - The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph3As=O complex generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)2(Ph3As=O)2 (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph3As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)3 for accelerating the epoxidations while maintaining high ee's is discussed.

AB - The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph3As=O complex generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)2(Ph3As=O)2 (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)3, BINOL, and Ph3As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph3As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)3 for accelerating the epoxidations while maintaining high ee's is discussed.

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