R. Andreatta, V. Nair, A. Robertson
1967
Citations
0
Influential Citations
27
Citations
Journal
Australian Journal of Chemistry
Abstract
cis- and trans-4-Chloro- and 4-bromo-L-prolines have been synthesized stereospecifically, the key step being SN2 displacement of a free or substituted 4-hydroxyl group in suitably protected 4-hydroxy-L- prolines. Similar displacements with azide ion followed by reduction provide convenient routes to cis- and trans- 4-amino-L-proline. A less satisfactory pathway to cis-4-aminoproline is reduction of a 4- oximinoproline derivative. In the course of the syntheses, which involve a variety of protecting groups, 45 new L-proline derivatives have been prepared. Unexpected side reactions were the formation of cis-4-hydroxyprolinamide by the action of ammonia on trans-4- bromoproline, and the reduction by sodium borohydride of N- benzyloxycarbonyl-4-oximinoproline methyl ester to N-benzyloxycar- bonyl-4-oximinoprolinol.