A practical concern associated with the proposed transformation is the possibility of competing Darzens reaction 1a,b,d,5 to produce the corresponding α,β-epoxy thioesters (Scheme 1). However, our previous experiences led us to believe that the magnesium aldolate intermediate would be sufficiently stable under the reaction conditions to prevent epoxide formation. To test this, we attempted the aldol addition with aldehyde 1 and α-bromo thioester 2 under our ...
