Abstract Enantiospecific synthesis of variously substituted cis-β-lactams can be achieved by the annelation of Schiff bases from optically active ketal aldehydes derived from D- threonine. Similar annelation of Schiff bases from the triphenylsilyl ether of D-threonine ester and cinnamaldehyde leads to cis-β-lactams with high diastereofacial selectivity.
