Metal-catalyzed reactivity reversal in the sulfonylation reaction of α-allenols: controlled synthesis of 4-(arylsulfonyl)-2,5-dihydrofurans

Abstract

The synergy between metal catalysis and radical chemistry allows to surpass previous limitations of the reactions between allenols and sulfonylating reagents. Considering that previous studies of the reactivity of the allenol moiety with sulfonylating reagents have been limited to addition and rearrangement reactions lacking cyclization, we decided to modify the protocol for achieving a catalytic cyclization/functionalization. In this way, we accomplished a copper-catalyzed cascade cycloetherification/sulfonylation for the controlled preparation of 4-(arylsulfonyl)-2,5-dihydrofurans from allenols and sulfinates involving in situ-generated sulfur-centered radicals. The generality of our strategy was illustrated using various methyl- and phenyl-substituted allenes.