γ-Substituted Allenic Amides in the Phosphine-Catalyzed Enantioselective Higher Order Cycloaddition with Azaheptafulvenes

Org Lett. 2020 Jun 19;22(12):4721-4725. doi: 10.1021/acs.orglett.0c01523. Epub 2020 May 28.

Abstract

Racemic γ-substituted allenes undergo enantioselective higher order [8 + 2]-cycloaddition with azaheptafulvenes using a chiral amino acid derived amidophosphine as catalyst, providing the corresponding azaazulenoid cycloadducts with excellent levels of regio-, diastereo-, and enantioselectivities. In this reaction, the activated allylic phosphonium ylide intermediate participates as the C2-component of the reaction, in contrast to the conventional reactivity of this type of zwitterionic intermediates as C3-components in cycloaddition reactions.

Publication types

  • Research Support, Non-U.S. Gov't