Organocatalytic Asymmetric Formal [3+3]-Cycloaddition to Access 2,3-Diazaspiro[4.5]deca-3,6-dien-1-ones

Abstract

Medicinally important 2,3-diazaspiro[4.5]deca-3,6-dien-1-ones having vicinal quaternary centers were constructed in very good yields with high enantio- and diastereoselectivities through an organocatalytic formal [3+3]-cycloaddition or domino Michael/aldol reactions, which is driven by the double sequence of in situ isoaromatization and dearomatization steps from the α-arylidene pyrazolinones and (E)-alkyl 2-oxo-4-arylbut-3-enoates.