Synthesis of β-Lactams from β-Amino acids with organophosphorus compounds as condensing reagents

Abstract

$\beta$-Lactam formation via the dehydration of $\beta$-amino acids has been developed using organophosphorus condensing reagents, which include Bis(5``-nitro-2``-pyridyl)-2,2,2-trichloroethyl phosphate and Bis(2,2,2-trichloroethyl)-5``-nitro-2``-pyridyl phosphate. The former reagent is much more effective than the latter. Using Bis(5``-nitro-2``-pyridyl)-2,2,2-trichloroethyl phosphate as a condensing reagent, N-substituted $\beta$-amino acids are cleanly cyclized into the corresponding $\beta$-lactams in high yields in acetonitrile or methylene chloride at room temperature, while the present method appeared to be less effective in the formation of $\beta$-lactams from N-unsubstituted $\beta$-amino acids.