6-endo-dig Cyclization of heteroarylesters to alkynes promoted by Lewis acid catalyst in the presence of Brønsted acid
摘要:
We report a regiocontrolled 6-endo-dig cyclization of 2-(2-arylethynyl)heteroaryl esters occurred under Bronsted acidic conditions and in the presence of a catalytic amount of Lewis acids such as Cu(OTf)(2), AUCl(3), or (CF3CO2)Ag. A variety of heteroc yclic lactones are readily prepared in excellent yields. (C) 2007 Elsevier Ltd. All rights reserved.
N-carbamoyl-2-carboxyaryl-heterocyclic and hydrazinecarboximidamide-hydrazone derivatives, intermediates and processes for their preparation, agricultural compositions containing them and their use as agricultural chemicals, in particular herbicides.