CONVERSION OF BETA-AMINO ESTERS TO BETA-LACTAMS VIA TIN(II) AMIDES

Addition of Sn[N(TMS)2]2 to beta-amino esters with sterically nondeman ding substituents at C3 or on nitrogen gave beta-lactams in 76-100% yi eld. More sterically demanding beta-amino esters could be converted to beta-lactams in excellent yield using unsymmetrical tin(II) amide rea gents which were prepared in situ. Optimal results for the in situ pro cedure involved addition of Sn[N(TMS)2]2 to a beta-amino ester, follow ed by addition of either pivalic acid or N-tert-butylacetamide.