pungent principle of hot pepper, and its 15 analogs have been efficiently synthesized. The key step of this synthetic sheme is the orthoester Claisen rearrangement, which transformed allylic alcohols 2A-C to (E)-alkenoates 3A-C () in a highly stereoselective manner. The subsequent carbon chain elongations on 3 based on the cyanation or the malonic acid estersynthesis afforded (E)-alkenoic acids 8, which