Tandem Claisen Rearrangement/6‐endo Cyclization Approach to Allylated and Pren­ylated Chromones

Abstract Allyl, dimethylallyl and prenyl ethers derived from o ‐acylphenols reacted upon microwave irradiation to form C ‐allylated or ‐prenylated chromone derivatives, depending on the substitution pattern of the arene and the allyl substituent. The reaction proceeds through a tandem Claisen rearrangement and 6‐ endo ‐ trig or 6‐ endo ‐ dig cyclization sequence. For prenyl ethers, the tandem sequence can be extended by a Cope rearrangement to furnish 6‐prenylchromones. The method is potentially useful for the synthesis of natural products and drugs.