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An asymmetric synthesis of the key precursor to (−)-indolizomycin

✍ Scribed by Michael D. Groaning; A.I. Meyers

Publisher
Elsevier Science
Year
1999
Tongue
French
Weight
265 KB
Volume
40
Category
Article
ISSN
0040-4039

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✦ Synopsis

Using chiral bicyclic lactams, containing an oc,fi-unsaturation, the key precursor of (-)-indolizomycin was obtained in optically pure form. The sequence involved a >20:1 diastereoselective cyclopropanation of the unsaturated lactam 5 employing sulfoxonium methylide. Tic14 mediated addition of allyltrimethylsilane afforded pyrrolidone 7 in a diastereomeric ratio of ~20: 1. The appropriately substituted pyrrolidone 2 was prepared by debenzylation and subsequent alkylation with 3-bromoproponic ester. The six step sequence from commercially available starting materials was performed in 26% overall yield.

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An efficient asymmetric synthesis of key
An efficient asymmetric synthesis of key intermediates in the synthesis of aphanorphine and eptazocine
✍ Stephen K. Taylor; Milica Ivanovic; Lloyd J. Simons; Matthew M. Davis 📂 Article 📅 2003 🏛 Elsevier Science 🌐 English ⚖ 190 KB

Efficient, formal syntheses of aphanorphine and eptazocine are reported that involve epoxide cyclizations. The necessary chiral epoxides were prepared following treatment of diols prepared by Sharpless asymmetric osmylations of an alkene. The cyclizations formed a ring compound with the same enantio