Synthetic Studies Directed Towards Various Homologues of Natural Sesquiterpene-Coumarin Ethers: The Domino Approach

摘要

A domino-based strategy was used to construct analogues containing the basic skeleton of the monocyclic sesquiterpene-coumarin ethers galbanic acid (1) and secodrial (3), through conversion of the domino adduct 19 into 10 and 11, chosen as representative targets. H-1 NMR patterns, corroborated by X-ray crystallographic analysis for two of the four possible diastereomeric arrangements of the six-membered B-ring common to various A-seco terpenes, have been determined. The observed trends help in the design of substituent combinations that provide a tool for diastereomeric recognition, depending on the cis/trans arrangement of the adjacent methyl groups and the adopted conformations.