New approach for two chromene carboxylic acids having a fully substituted benzene ring

Two chromene carboxylic acids having a fully substituted benzene ring, 8-chlorocannabiorcichromenic acid (1) and mycochromenic acid (2), were synthesized via thermal cyclization of the corresponding four substituted phenyl propargyl ethers. (C) 2004 Elsevier Ltd. All rights reserved.