Highly efficient intramolecular cyclizations of 2′-hydroxychalcones to 4-chloro-2<i>H</i>-chromenes under vilsmeier conditions
作者:Zhen-Hua Li、Cun Zheng、Wei-Ke Su
DOI:10.1002/jhet.5570450441
日期:2008.7
Highlyefficientintramolecularcyclization and of 2′-hydroxychalcones to 4-chloro-2H-chromenesunderVilsmeierconditions 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 chemselectivity, higher yields and avoids the formation of inorganic phosphorus
Highly efficient access to 4-chloro-2H-chromenes and 1,2-dihydroquinolines under mild conditions: TMSCl-mediated cyclization of 2-propynolphenols/anilines
novel and efficient TMSCl-mediated cyclization reaction of easily prepared 2-propynolphenols/anilines is developed to give 4-chloro-2H-chromenes and 1,2-dihydroquinolines in good to efficient yields. It is noted that TMSCl acts not only as a promoter in this reaction, and also as the chloro source. Both tertiary and secondary propargylic alcohols with diverse functional groups were tolerated under mild