Phosphine-Mediated MBH-Type/Acyl Transfer/Wittig Sequence for Construction of Functionalized Furo[3,2-c]coumarins.

A new method for the construction of functionalized furo[3,2-c]coumarins via MBH-type/acyl-transfer/Wittig reaction is reported. The current approach would open a new route for the simultaneous formation of two rings in a one-pot reaction which is accompanied by incorporation of a keto functionality on the furan ring by activating the terminal alkynoates with phosphine. Furthermore, this protocol could also be applicable to the internal alkynoates/propiolamides to generate the 2,3-disubstituted furo[3,2-c]coumarins/furo[3,2-c]quinolinones by excluding the acyl-transfer reaction.