First synthesis of 4-oxo-6-trifluoromethyl-4H-thiopyran-2-carboxylic acid and its derivatives
作者:B. I. Usachev、S. A. Usachev、G.-V. Röschenthaler、V. Ya. Sosnovskikh
DOI:10.1007/s11172-010-0171-7
日期:2010.4
Treatment of 6-trifluoromethylcomanic acid with sodium hydrosulfide afforded for the first time 4-oxo-6-trifluoromethyl-4H-thiopyran-2-carboxylic acid (6-trifluoromethylthiocomanic acid). When heated or treated with H2SO4, this acid easily underwent decarboxylation leading to 2-trifluoromethyl-4H-thiopyran-4-one. Because of this, both ethyl and methyl 6-tri-fluoromethylthiocomanates were obtained in low yields (15–23%). Decarboxylation of 6-tri-(di)fluoromethylcomanic acids gave 2-tri(di)fluoromethyl-4H-pyran-4-ones in 77–80% yields.