CuCl-catalyzed cycloisomerization reaction of 1,2-allenyl carboxylic acids.: A cost-effective synthesis of β-unsubstituted butenolides

Fourteen examples of 2,3-butadienoic acids were synthesized according to the known procedures and their high-yielding CuCl-catalyzed cycloisomerization reaction to afford butenolides were described. (C) 2001 Elsevier Science Ltd. All rights reserved.