Studies toward the synthesis of arteminolide: [5+2] cycloaddition reactionof allenes with oxidopyrylium ions

The oxidopyrylium cycloaddition reaction of allenes was investigated. Contr ary to other cycloaddition reactions, electron deficient allenes were not r eactive at all and electron rich allenes were slightly more reactive than n eutral allenes. The intermolecular cycloaddition reaction occurred at the t erminal position regardless of substitution patterns. For the intramolecula r reaction only the perhydroazulene structure was obtained over other possi ble products. (C) 2001 Elsevier Science Ltd. All rights reserved.