SYNTHESIS OF PENTALENIC ACID THROUGH BIOGENETIC LIKE CYCLIZATION OF HUMULENE

Article abstract of DOI:10.1246/cl.1981.355

Humulene furnished 4,7-epoxy-3-methylene-7,10,10-trimethyl-11-bicyclo<6,3,0>undecanol 9 in 34percent yield employing oxymercuration as a key step.On treatment with BF3.OEt2, 7,11-dihydroxy-3,7,10,10-tetramethyl-3-bicyclo<6.3.0>undecene, which was derived from 9 by ether cleavage, afforded 10α-hydroxy-pentalenene 13 (20percent) along with four byproducts.Oxidation of allylic methyl group of 13 gave methyl pentalenate in 13percent yield from 9.