Highly efficient synthesis of 3a,6a-dihydrofuro[2,3-b]furans via a novel bicyclization.

A highly efficient method for the construction of 3a,6a-dihydrofuro[2,3-b]furan derivatives has been developed via a novel bicyclization, which is very valuable for the synthesis of fused furofuran compounds since it is time-saving and catalyst-free. Based on the bicyclization, a coupled domino strategy has been developed to directly construct 3a,6a-dihydrofuro[2,3-b]furan derivatives from methyl ketones.