LAUSR

Abstract An efficient and operationally simple strategy for the stereoselective synthesis of novel C -3 functionalized 3-sulfonyl-β-lactam heterocycles is described. The C -3 functionalized 3-phenyl/benzylsulfonyl-β-lactams 3/3′, 5/5′ has been synthesized via Michael addition using different Michael acceptors on trans -3-phenyl/benzylsulfonyl-β-lactams 2(a–f) using K 2 CO 3 as a base and acetonitrile/DMF as solvents. The reaction furnished exclusively cis- β-lactam adducts 3(a–r) using sterically less hindered Michael acceptors. Further, the effect of steric bulk and chiralilty of Michael acceptors was explored to achieve target C -3 functionalized β-lactams 3(s-u)/3′(s-u) and 5(a–c)/5′(a–c) . The structural and stereochemical analysis of novel β-lactams were carried out using FT-IR, NMR ( 1 H, 13 C, 1 H- 1 H COSY, 1 H- 13 C COSY and 13 C DEPT-135), elemental analysis (CHNS), mass spectrometry (EIMS and LCMS) in representative cases and single crystal X-ray crystallographic studies ( 3e ). The cis or trans configuration of the Michael acceptor (E) at C-3 was assigned with respect to C4-H.