Organocatalytic synthesis of N-phenylisoxazolidin-5-ones and a one-pot synthesis of β-amino acid esters

A novel N-heterocyclic carbene (NHC)-catalyzed C-N bond formation by the reaction of alpha,beta-unsaturated aldehydes and nitrosobenzene to N-phenylisoxazolidin-5-ones, followed by an acid-catalyzed esterification and Bamberger-like rearrangement in a mild one-pot protocol leads to N-p-methoxyphenyl (N-PMP) protected beta-amino acid esters.