Carbocyclic Ring Formation by the Intramolecular Reaction between Enol Silyl Ether and Allylic Acetate Moieties

Article abstract of DOI:10.1246/bcsj.53.2050

The title reaction of trans-3-acetoxy-4-(4-methyl-3-trimethylsiloxy-3-pentenyl)cyclohexene proceeds in the presence of Et2AlOAr, where Ar=2,6-di-t-butyl-4-methylphenyl, affording stereospecifically the cis isomer of 2,2-dimethylbicyclo<4.4.0>dec-9-en-3-one.In contrast, the cis-disubstituted cyclohexene compound reacts only sluggishly to produce a mixture of the cis- and trans-fused octalones.Similar stereospecific effect of the allylic double bond configuration on the ease of cyclization has been observed in the synthesis of karahanaenone from 3,7-dimethyl-6-trimethylsiloxy-2,6-octadienyl acetate and related reactions.