Header

UZH-Logo

Maintenance Infos

The asymmetric synthesis of fused cyclopentenone ring systems: a formal asymmetric total synthesis of (−)-isocomene


Meyers, Albert I; Bienz, Stefan; Kwon, Hyok-Boong; Wallace, Richard H (1996). The asymmetric synthesis of fused cyclopentenone ring systems: a formal asymmetric total synthesis of (−)-isocomene. Helvetica Chimica Acta, 79(4):1026-1046.

Abstract

Optically active tricyclic oxazolidine lactams 10 have been prepared using two different routes (Scheme 1). They can be obtained by acid-mediated intramolecular cyclization of bicyclic lactams 13via their acyliminium intermediates producing appended five-, six-, and seven-membered tricyclic systems. Alternatively, 10 can be prepared by cyclocondensation of chiral amino alcohols with cyclopentane-1,2-dicarboxylic acids 12 to give the imide which is reduced or alkylated to the amino alcohols and cyclized to a diastereoisomer mixture of 10. Alkylation of 10 (R″ = H) via its enolate gives stereospecifically α-quaternary products 10 (R″ = alkyl). Degradation of the latter with MeLi or Red-Al® followed by mild acid hydrolysis and aldol cyclization produces the bicyclic ketones 14 and 15 as 1:1 mixtures, readily separated and isolated in > 99% ee. This sequence produced a known non-racemic intermediate 69 for the synthesis of (−)-isocomene.

Abstract

Optically active tricyclic oxazolidine lactams 10 have been prepared using two different routes (Scheme 1). They can be obtained by acid-mediated intramolecular cyclization of bicyclic lactams 13via their acyliminium intermediates producing appended five-, six-, and seven-membered tricyclic systems. Alternatively, 10 can be prepared by cyclocondensation of chiral amino alcohols with cyclopentane-1,2-dicarboxylic acids 12 to give the imide which is reduced or alkylated to the amino alcohols and cyclized to a diastereoisomer mixture of 10. Alkylation of 10 (R″ = H) via its enolate gives stereospecifically α-quaternary products 10 (R″ = alkyl). Degradation of the latter with MeLi or Red-Al® followed by mild acid hydrolysis and aldol cyclization produces the bicyclic ketones 14 and 15 as 1:1 mixtures, readily separated and isolated in > 99% ee. This sequence produced a known non-racemic intermediate 69 for the synthesis of (−)-isocomene.

Statistics

Citations

9 citations in Web of Science®
9 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

0 downloads since deposited on 24 Aug 2017
0 downloads since 12 months

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:26 June 1996
Deposited On:24 Aug 2017 16:26
Last Modified:25 Aug 2017 07:38
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0018-019X
Publisher DOI:https://doi.org/10.1002/hlca.19960790412

Download

Preview Icon on Download
Content: Published Version
Language: English
Filetype: PDF - Registered users only
Size: 1MB
View at publisher