SYNTHESIS OF N-FMOC-ALPHA-AMINO ACIDS CARRYING THE 4 DNA NUCLEOBASES IN THE SIDE-CHAIN

Four new N-Fmoc alpha-amino acids carrying a nucleobase in the side ch ain were prepared starting from L-glutamic acid. N-Boc-glutamic acid a lpha benzyl ester underwent a radical decarboxylation in the presence of CBrCl3 to give the corresponding 2-amino-4-bromobutanoic acid deriv ative. The four nucleobases (adenine, cytosine, thymine and guanine) w ere introduced ''via'' nucleophilic substitution of the bromide using a different synthetic protocol for each base. The Boc protection was c hanged to Fmoc and the benzyl ester deprotected to give the four amino acids in good yields and in a suitable form For solid phase peptide s ynthesis. The preparation of the insecticidal dipeptide NK 374200 is a lso described. Copyright (C) 1996 Elsevier Science Ltd