Highly efficient intramolecular cyclizations of 2 '-hydroxychalcones to 4-chloro-2H-chromenes under Vilsmeier conditions

摘要

Highly efficient intramolecular cyclization and of 2'-hydroxychalcones to 4-chloro-2H-chromenes under Vilsmeier conditions have been developed. In comparison with the reported methods, studies carried out indicate that Vilsmeier reagent generated in situ from DMF and bis(trichloromethyl) carbonate (BTC) provides excellent chem selectivity, higher yields and avoids the formation of inorganic phosphorus salts.