A STUDY OF THE REACTIVITY OF (METHYL 2-ACETAMIDOACRYLATE)-TRICARBONYLIRON(0) LEADING TO A NOVEL SYNTHESIS OF BETA,BETA,BETA-TRIALKYL ALPHA-AMINO-ACIDS

(Methyl 2-acetamidoacrylate)tricarbonyliron(0) (3) reacts with 2 equivalents of methyllithium to give methyl N-acetylalaninate (4) and 2-acetamido-4-oxopentanoate (5) when the reaction is quenched with trifluoroacetic acid. Production of methyl N-acetylalaninate is dependent only on the presence of trifluoroacetic acid, and the ratio of 4 to 5 generated in these reactions is related to the quantity of trifluoroacetic acid used to quench them. Addition of two equivalents of methyllithium followed by tertiary haloalkanes gives protected beta,beta,beta-trialkyl alpha-amino acids which may be hydrolysed to give tert-leucine (13) and the new alpha-amino acids 2-amino-3,3-dimethylpentanoic acid (14) and 2-amino-3,3-dimethylhexanoic acid (15).