Enantioselective deprotonative ring contraction of N1-methyl-N4-Boc-benzo[e][1,4]diazepine-2,5-diones.

N1-Methyl-N4-Boc-benzo[e][1,4]diazepine-2,5-diones were prepared in good yield and high stereochemical purity from five amino acids. Upon deprotonation, these compounds undergo ring contraction to the corresponding quinolone-2,4-diones with high enantioselectivity, providing efficient entry to a potentially useful drug scaffold. Mechanistic commentary and comparisons to related reactions are provided.