| 摘要 |
PROBLEM TO BE SOLVED: To efficiently obtain the above compound useful as a synthetic intermediate for various physiologically active substances by carrying out specific reaction of a specific compound in the presence of a metal halide. SOLUTION: (A) An 4-alkoxy-2-cyclopentene-1-one of formula I (R is a 1-10C alkyl) is subjected to Diels-Alder reaction with (C) cyclopentadiene in the presence of (B) a metal halide (preferably a zinc halide or a titanium halide) to afford an isomer mixture of Diels-Alder adducts represented by formula Hand formula III, which is then passed through dealkylation process using a titanium compound (preferably titanium halide) and dehydration process under basic conditions to provide the objective compound of formula IV. |
