Highly diastereoselective [3+3] cycloaddition of indolin-3-ones and nitroallylic acetates: Efficient access to polysubstituted dihydropyrano[3,2-b]indoles

Abstract

Dihydropyrano[2,3-b]indole is a privileged indoline motif, while its analog, dihydropyrano[3,2-b]indole, had been much less explored. Herein, the highly diastereoselective [3 + 3] cycloaddition of indolin-3-ones with nitroallylic acetates were developed for the efficient synthesis of a series of polysubstituted dihydropyrano[3,2-b]indoles in good to high yields with exclusive diastereoselectivities. Different from previous reports, this approach employed a base-promoted cycloaddition strategy to assemble pharmacologically interesting dihydropyrano[3,2-b]indole scaffolds.