The tetramethylallyl cation as a surrogate for the epoxide function as an initiator of biomimetic polyene pentacyclizations. Total synthesis of sophoradiol
作者:Paul V Fish、William S Johnson
DOI:10.1016/s0040-4039(00)76734-7
日期:1994.3
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 totalsynthesis of the pentacyclictriterpenoid 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
Three new olean-12-ene derivatives (1-3), together with known urs-12-ene-3beta, 28-diol (4) were isolated from the stem root of Cylicodiscusgabunensis. The structures of the new compounds were established by chemical and spectroscopic means as beta-amyrin-n-nonyl ether (1), 22alpha-hydroxyolean-12-en-3beta-yl-beta-D-galactopyranoside (2), and 24-hydroxyolean-12-en-3beta-yl-beta-D-glucopyranoside (3)