Synthetic Transformations of Sesquiterpene Lactones 10*. Synthesis of 13-Arylguaianolides

Abstract

The Heck reaction of methylidene lactones of guaiane type, arglabin and ludartin, with aryl halides occurs with the formation of the respective (E)- and (Z)-13-arylidene-substituted derivatives and the respective endocyclic isomer, the ratio of which depends on the nature of methylidenelactone and the reaction conditions. The arylation of ludartin occurred with a lower yield of the target products and was accompanied by the formation of chamazulene. The interaction of grosheimin with aryl halides under Heck reaction led to the exocyclic products with (E)- and (Z)-configuration, with the latter as the major isomers. The structure of two compounds was established by X-ray structural analysis.