THE TETRAMETHYLALLYL CATION AS A SURROGATE FOR THE EPOXIDE FUNCTION AS AN INITIATOR OF BIOMIMETIC POLYENE PENTACYCLIZATIONS - TOTAL SYNTHESIS OF SOPHORADIOL

[摘要] The tetramethylallyl cation has proven to be an effective substitute for the epoxide as an initiator for biomimetic polyene cyclizations. This methodology was applied to the total. synthesis of the pentacyclic triterpenoid sophoradiol (1) whereby the key step of the strategy involved the protic acid-catalyzed pentacyclization of tetramethylallyl alcohol 9 which furnished fluoropentacycle 11 as the major product in 31% yield. Lewis acid-catalyzed cyclization of 9 gave the dehydrofluorinated pentacycle 12 in 50% yield.

[发布日期] 1994-03-07