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Enantioselective [2,3]-sigmatropic and [1,2]-Stevens rearrangements via intramolecular formation of allylic oxonium ylides catalyzed by chiral dirhodium(II) carboxylates

✍ Scribed by Shinji Kitagaki; Yoshimasa Yanamoto; Hideyuki Tsutsui; Masahiro Anada; Makoto Nakajima; Shunichi Hashimoto

Publisher
Elsevier Science
Year
2001
Tongue
French
Weight
79 KB
Volume
42
Category
Article
ISSN
0040-4039

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✦ Synopsis

Tandem intramolecular generation and rearrangement of allylic oxonium ylides from a-diazo b-keto esters has been effected with the aid of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] in toluene, providing benzofuran-3-ones via [2,3]-sigmatropic rearrangement in up to 76% ee. In systems with crotyl and prenyl substituents, products arising from the less common [1,2]-Stevens rearrangement as a side reaction have also been obtained in up to 66% ee. It is suggested that competitive [2,3]-and [1,2]-rearrangements proceed through a common, chiral rhodium(II)-bound oxonium ylide intermediate.

πŸ“œ SIMILAR VOLUMES

Corrigendum to β€œEnantioselective [2,3]-s
Corrigendum to β€œEnantioselective [2,3]-sigmatropic and [1,2]-Stevens rearrangements via intramolecular formation of allylic oxonium ylides catalyzed by chiral dirhodium(II) carboxylates”: [Tetrahedron Letters 42 (2001) 6361]
✍ Shinji Kitagaki; Yoshimasa Yanamoto; Hideyuki Tsutsui; Masahiro Anada; Makoto Na πŸ“‚ Article πŸ“… 2001 πŸ› Elsevier Science 🌐 French βš– 27 KB

In this paper, the authors describe the tandem oxonium ylide formation and [2,3]-sigmatropic rearrangement from 1b using Rh 2 (R-DDBNP) 4 (up to 62% ee).