PHENYLALANINE DERIVATIVES PREPARED BY NITRATION OF PHENYLALANINE, FOLLOWED BY REDUCTION AND REACTION WITH DIPHENYLCYANOCARBONIMIDATE; PEPTIDE SYNTHESIS

摘要

Unnatural amino acids are provided which can be incorporated into peptides which either inhibit or promote the secretion of gonadotropins by the pituitary gland and inhibit the release of steroids by the gonads. These unnatural amino acids are useful in the synthesis of peptides and have the formula (a): where W is (CH2)n or n is an integer from 1 to 6; j=1,2 or 3, and preferably, Y is N-CN, X is NH and R2 is alkyl, modified alkyl, alkenyl, alkynyl, aryl or methyl pyridyl; or the formula (b): where R11 is H or acyl and W is as defined in (a), and preferably R11 is H and W is Disclosed are peptides that are analogs of the decapeptide GnRH wherein there is at least one residue of an unnatural amino acid in the 3-, 5-, 6- and/or 8-positions.