ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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 13 via 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.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19960790412
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