New synthesis of cis 5-tert-butyl-L-proline via cuprate. Evaluation as a cis proline mimetic in a biological active octapeptide.

ABSTRACT

cis 5-tert-butyl-L-proline (Cbp) was prepared rapidly and efficiently by the addition of low-valent tert-butyl cuprate to an aminal derived from proline. [Cbp(2), D-Leu(5)]-OP was then synthesized, showing a predominant cis peptide bond conformation, as confirmed by NMR.