Synthesis of novel N-(4-ethoxyphenyl) azetidin-2-ones and their oxidative N-deprotection by ceric ammonium nitrate

It is shown that the N-(p-ethoxyphenyl) group on beta-lactams can be oxidatively removed by ceric ammonium nitrate in good yield. Fourteen new N-(p-ethoxyphenyl)-2-azetidinones 8a-n were synthesized through standard [2+2] ketene-imine cycloadditions (Staudinger reaction). Treatment of these compounds with ceric ammonium nitrate yielded the N-dearylated 2-azetidinones 9a-n in good to excellent yields. The effects of solvent, molar equiv of CAN and different temperatures have been investigated and optimum conditions were established.