The Enantioselective Synthesis of β‐Amino Acids, their α‐hydroxy derivatives, and the N‐terminal components of bestatin and microginin

Abstract L ‐Aspartic acid by tosylation, anhydride formation, and reduction with NaBH 4 was converted into (3 S )‐3‐(tosylamino)butan‐4‐olide ( 8 ; Scheme 1 ). Tretment of 8 with ethanolic trimethylsilyl iodide gave the N ‐protected deoxy‐iodo‐β‐homoserine ethyl ester 9 . The latter, on successive nucleophilic displacement with lithium dialkyl‐cuprates ( → 10a–e ), alkaline hydrolysis ( → 11a–e ), and reductive removal of the tosyl group, …