Unexpected formation of new chiral 3-amino-5-alkyl-2,5-dihydro-1H-pyrrolin-2-ones from N-Boc-α-amino esters

We describe a one-pot process involving the DiBAl-H reduction of the ester moiety of N-protected α-amino esters, followed by Horner–Wadsworth–Emmons olefination in the presence of the trimethyl ester phosphonoglycinate carbanion allowing the formation of new chiral 3-amino-5-alkyl-2,5-dihydro-1H pyrrolin-2-one 5. The Z-enoate 4b, which is formed during this reaction, could be converted into the corresponding lactam 5b under UV irradiation with the presence of BuLi.