Direct multicomponent synthesis of benzocoumarins

A straightforward and versatile protocol for the synthesis of dibenzo[b,d]pyran-6-ones from readily available 3-carbonylcoumarins is reported. Our strategy is based on a reaction cascade of successive [4+1] and [4+2] cycloadditions that occur in one single operation. This work illustrates the unprecedented use of a multicomponent reaction of isocyanides for the preparation of this biologically relevant type of compounds. Notably, in this highly convergent and atom-economic process, one new single and two new double carbon-carbon bonds are formed in a simple synthetic operation.