Regioselective nitration of N~(alpha)-bis(trifluoroacetyl)-L-tryptophan methyl ester: Efficient synthesis of 2-nitro and 6-nitro-N-trifluoroacetyl-L-tryptophan methyl ester

摘要

Nitration of N~(alpha),N~1-bisttrifluoroacetyl)-L-tryptophan methyl ester with HNO_3 in acetic anhydride at 0 degC provides N~(alpha)-trifluoroacetyl-2-nitro-L-tryptophan methyl ester in 67% yield, whereas nitration in trifluo-roacetic acid at 0 degC gives N~(alpha)-trifluoroacetyl-6-nitro-L-tryptophan methyl ester in 69% yield.