Synthesis of 2,2-Dimethyl-2<i>H</i>-thiochromenes, the Sulfur Analogs of Precocenes
作者:J. Tércio、B. Ferreira、V. Catani、J. V. Comasseto
DOI:10.1055/s-1987-27866
日期:——
A new general synthesis of 2,2-dimethyl-2H-thiochromenes in good yield consists of the Michael addition of thiophenols to 3-methyl-2-butenoic acid, intramolecular cyclocondensation of the resultant 3-methyl-3-phenylthiobutanoic acids, reduction of the 2,2-dimethyl-4-oxothiochromenes thus obtained with sodium borohydride, and acid-catalyzed dehydration of the resultant 4-hydroxy-2,2-dimethylthiochromans.