Synthesis of 2,3-disubstituted indoles via a tandem reaction

Abstract

A strategy for the synthesis of 2,3-disubstituted indoles from 2-allyl-2-(2-nitrophenyl)cyclohexane-1,3-dione has been developed. A wide array of 2,3-disubstituted indoles were accessed in modest to good yields via a tandem reduction/condensation/fragmentation/cyclization sequence. The utility of this strategy was exemplified in the formal syntheses of leucomidine A and goniomitine. The mechanism was confirmed by experiments and density functional theory (DFT) calculations. Differential fragmentation made the reaction more complicated.