Synlett 2004(10): 1739-1742  
DOI: 10.1055/s-2004-829577
LETTER
© Georg Thieme Verlag Stuttgart · New York

Manganese-Catalyzed Oxidative Transformation of Silyl Ethers to Ketones: Enantioselective Synthesis of Optically Active β- and γ-Siloxyketones

Shun-Ichi Murahashi*a,b, Satoru Nojib, Tatsuo Hirabayashib, Naruyoshi Komiyab
a Department of Applied Chemistry, Faculty of Engineering, Okayama University of Science, 1-1, Ridai-cho, Okayama, Okayama 700-0005, Japan
Fax: +81(86)2564292; e-Mail: murahashi@high.ous.ac.jp;
b Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3, Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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Publikationsverlauf

Received 2 May 2004
Publikationsdatum:
15. Juli 2004 (online)

Abstract

(Salen)manganese(III)-catalyzed oxidation of silyl ethers with iodosylbenzene gave the corresponding carbonyl compounds. The enantioselective oxidation of symmetrical 1,3- and 1,4-disilyl ethers gave the corresponding optically active b- and g-sil­oxyketones, respectively (up to 93% ee).

20

The absolute configuration of 6 was determined after converting to the corresponding (R)- and (S)-α-methoxy-α-(trifluoromethyl)phenylacetic acid esters (MTPA esters).

21

The absolute configuration of 8 was assigned in comparison with the reported optical rotation value after converting to 4-hydroxytetralone. [13]

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Solvent CH2Cl2, 10 °C; [silyl ether] = 2.0 × 10-1 M; [1] = 1.0 × 10-3 M; [PhIO] = 2.0 × 10-2 M.