2-Methylcyclopent-2-en-1-one (1, Scheme 1) is a classic starting
material often used for syntheses of steroids and polycyclic terpenoids.1,2
Conjugate addition of nucleophilic carbon unit R1 to 1
followed by the enolate trapping and subsequent reaction with
electrophilic R2 leads to trans-adduct 2 with a high diastereoselectivity