Regioselective synthesis of pyrimidine-annulated spiro-dihydrofurans by silver-catalyzed 5-endo-digcyclization

Abstract

A simple and efficient method for the synthesis of some hitherto unreported pyrimidine-annulated spiro-dihydrofurans has been described. In the presence of AgSbF₆ spiro- and furo-pyrimidine (10-hydroxy-4,7,9-substituted-1-oxa-7,9-diazaspiro[4.5]dec-3-ene-6,8-dione) heterocycles are obtained in good yields. The nature of the alkyne moiety present in substrates dictates the mode of cyclization to form the furopyrimidine derivatives.