J. Hondrelis, G. Lonergan, S. Voliotis
1990
Citations
0
Influential Citations
29
Citations
Journal
Tetrahedron
Abstract
Abstract Proline, 4-hydroxyproline, azetidine-2-carboxylic acid, pipecolic acid and proline containing dipeptides were converted to N-t-butyloxycarbonyl, O-phenacyl derivatives in a one pot synthesis. 1 H - and 13 C -NMR spectroscopy of certain derivatives (Boc-Pro-PE, Boc-4Hyp-PE, Boc-Pro-4BrPE and Boc-Pip-PE) in CDC1 3 solution reveal the presence of cis-trans isomers in almost equal quantities. On the contrary, the 1 H- and 13 C -NMR spectra of the N-t-butyloxycarbonyl phenacyl ester of azetidine-2-carboxylic acid, show the presence of one isomer only. Similarly, only one urethane isomer was observed in solution for the protected C-terminal angiotensin II dipeptides, N-t-Boc-Pro-Phe-PE and N-t-Boc-Pro-Ile-PE. All phenacyl derivatives exhibited magnetic asymmetry attributed to steric factors.