Conformational mimicry. 3. Synthesis and incorporation of 1,5-disubstituted tetrazole dipeptide analogs into peptides with preservation of chiral integrity: bradykinin

The simple addition of the organic base,quinoline,to the reaction with PCl 5 when generating an imidoyl chloride from the amide was effective in reducing racemization of the N-terminal amino acid residue of the protected tetrazole dipeptide to miminal levels.The use of Z for amino protection and benzyl ester for carboxyl protection with differential removal of the Z group by HBr/HOAc has proven a pratical route to a wide variety of tetrazole dipeptides