Method for the Preparation of N‐protected β‐Cyano L‐alanine Tertiary Butyl Esters

Abstract

AbstractHere we report a simple, efficient and scalable one‐pot procedure for the synthesis of N‐protected β‐cyano L‐alanine tertiary butyl esters from N‐protected L‐asparagines. Reaction of N‐protected L‐asparagines with 2.2 equivalents of (Boc)2O and catalytic amount of N,N‐dimethylamino pyridine (DMAP) in tertiary butanol at room temperature resulted N‐protected β‐cyano L‐alanine tertiary butyl esters. We also synthesized N‐protected β‐cyano L‐alanines from the obtained crude N‐protected β‐cyano L‐alanine tertiary butyl esters without column chromatography on gram scale in good yields. Control experiments gave the corresponding nitrile acids over the tertiary butyl esters. Later, we synthesized nitrile containing dipeptides by coupling N‐Boc‐β‐cyano L‐alanine 4 a with amino acid methyl ester hydrochlorides.