Optically active tricyclic oxazolidine lactams 10 have been prepared using two different routes (Scheme I ).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 a-quaternary products 10 ( R = alkyl). Degradation of the latter with MeLi or Red-AP followed by mild acid hydrolysis and aldol cyclization produces the bicyclic ketones 14 and 15 as 1 :I mixtures, readily separated and isolated in > 99% ee. This sequence produced a known non-racemic intermediate 69 for the synthesis of (-)-isocomene.

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129ChemInform Abstract Vinyl triflates such as (I) undergo Pd(0)-catalyzed cross-coupling reaction with the stannane (II) to yield dienes such as (III) which are hydrolyzed to give α,β-unsaturated ketones such as (IV). The analogous procedure with phenyl triflate (V) results n the formation of acetophenone (VI). In the presence of carbon monoxide (VII), ethoxyvinyl ketones (VIII) are obtained which are hydrolyzed to give the α-diketones (IX). Numerous further examples are given in the original paper.