Asymmetric Cascade Dearomatization–Cyclization Reaction of Tryptamines with β,γ-Alkynyl-α-imino Esters: Access to Hexahydropyrrolo[2,3-<i>b</i>]indole-Containing Tetrasubstituted α-Amino Allenoates

Abstract

]indole-containing tetrasubstituted α-amino allenoates, exhibiting both axial and central chirality, has been accomplished via cascade dearomatization-cyclization reaction. The γ-addition to β,γ-alkynyl-α-imino esters provides a library of densely substituted highly enantioenriched allenes in high yields and excellent stereoselectivities. In addition, the scope of this methodology has been extended to tryptophol as well. A scale-up reaction and synthetic transformations of the products were performed to demonstrate the practical usefulness of this approach.

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