N-Boc-α-tosylsarcosine ethyl ester: An α-amido sulfone for the regio- and stereoselective synthesis of protected γ,δ-unsaturated n-methyl-α- amino acids by palladium-catalyzed nucleophilic substitution

Article abstract of DOI:10.1016/S0040-4039(97)10054-5

N-Boc-α-tosylsarcosine ethyl ester (3) reacts under neutral conditions either with allylic carbonates or with vinyloxirane in the presence of a catalytic mount of Pd(PPh₃)₄ and dppe (5 mol%) to give regio- and stereoselectively the corresponding allylated products 5 and 6, respectively. Reductive desulfonylation of these compounds with Mg-MeOH affords the corresponding protected γ,δ-unsaturated N-methyl-α-amino acids 7 and 8.