Notiz zur Synthese von 4‐Dialkylphosphono‐azetidinonen‐(2)

A New Approach to the Synthesis of 4-Phosphonylated β-Lactams

“…On the other hand, the known synthetic strategies to 4dialkoxyphosphonylazetidin-2-ones (Scheme 1) involve the Staudinger reaction of a phosphonylated azomethine with phthalylglycyl chloride in the presence of triethylamine, 18 the Michael-Arbuzov reaction of substituted 4-acetoxyazetidin-2-ones with trialkyl phosphites or diethyl methylphosphonite, [19][20][21][22] and a C3-C4 bond formation in the β-lactam ring by the intramolecular cyclization of phosphoruscontaining α-bromobutyramides 23 or α-(chloroacetamido)arylmethylphosphonates 24,25 in the presence of strong bases.…”