Synthesis of highly oxygenated enantiomerically pure cis-bicyclo[4.3.0]nonanes from secondary sugar allyltin derivatives
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Secondary sugar allyltin derivatives of the d-series: Sug-CH(SnBu3)-CH
CH2 (obtained in an SN2′ reaction of the corresponding primary allylic mesylates with ‘Bu3SnCu’) with the S-configuration at the stereogenic center bearing the -SnBu3 group decompose at 140°C to dienoaldehydes: CH2CH-CHCH-[(CHOR)3]-CHO with the cis geometry across the internal double bond. Such aldehydes react with the stabilized Wittig reagents to afford trienes, cyclization of which provides highly oxygenated enantiomerically pure cis-bicyclo[4.3.0]nonenes. This methodology is complementary to that recently proposed by us leading to such bicyclic systems, but with the trans junction between the five- and six-membered rings.
CH2 (obtained in an SN2′ reaction of the corresponding primary allylic mesylates with ‘Bu3SnCu’) with the S-configuration at the stereogenic center bearing the -SnBu3 group decompose at 140°C to dienoaldehydes: CH2CH-CHCH-[(CHOR)3]-CHO with the cis geometry across the internal double bond. Such aldehydes react with the stabilized Wittig reagents to afford trienes, cyclization of which provides highly oxygenated enantiomerically pure cis-bicyclo[4.3.0]nonenes. This methodology is complementary to that recently proposed by us leading to such bicyclic systems, but with the trans junction between the five- and six-membered rings.