DMF-DMA assisted novel Friedel-Crafts acylation of thiochroman

ORGN 109

Yuezhong Wen, Institute of Environmental Science, Zhejiang University,P.O. Box 1707, Hangzhou, 310027, China and Weiping Liu, Institute of Environmental Science, Zhejiang University,1707Box, Hangzhou, 310027, China.
The Friedel-Crafts acylation is a synthetic method of wild application. Commonly, acylhalides or anhydrides in the presence of aluminum chloride are used as reagent. However, electrophilic thiochroman with oxime, 5,8-Dimethyl-thiochroman-4-one O-methyl-oxime, was found that these classical conditions were not suitable and cannot give object compound. Similar reactions was reported that DMF-AlCl3 or DMSO- AlCl3 reagent give excellent yield. These methods also can give our object compound in low yield. Here we reported the synthesis of 6-Acetyl-5,8-dimethyl-thiochroman-4-one O-methyl-oxime in 80% yield employing the DMF-DMA reagent with acylhalide as acylating agent.