Synfacts 2010(6): 0644-0644  
DOI: 10.1055/s-0029-1219879
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Copper(II) Bromide/BoronTrifluoride Cocatalyzed Synthesis of Benzofurans

Contributor(s): Victor Snieckus, Alcides da Silva
Y. Liu, M. Wang*, H. Yuan, Q. Liu*
Northeast Normal University, Changchun, P. R. of China
Further Information

Publication History

Publication Date:
20 May 2010 (online)

Significance

A formal [3+2] cycloaddition ­between CuBr2-activated α-EWG ketene dithio­acetals 1 and BF3-activated p-quinones 2 provides benzofurans. Optimized reaction conditions were established using CuBr2 (20 mol%)/BF3 (10 mol%) in MeCN at room temperature. p-Quinones containing both electron-withdrawing and -donating substituents proved to be effective and gave ­benzofurans in good yields. On the other hand, o-quinone proved not to be a suitable substrate. Ketene dithioacetals 1 with a range of EWG were shown to be effective reaction partners. A possible mechanism for the catalytic activation of CuBr2 on α-EWG ketene dithioacetals 1 was ­proposed.