SYNTHESIS OF DIALKYL (PYRROLIDIN-2-YL)-PHOSPHONATES BY MERCURIC ACETATE PROMOTED CYCLIZATION OF α-AMINOALKENYLPHOSPHONATES. REGIO AND STEREOCHEMICAL ASPECTS

Abstract

A new series of dialkyl(pyrrolidin-2-yl)phosphonates was synthesized by regiospecific intramolecular aminomercuration of α-amino alkenylphosphonates followed by sodium borohydride reduction. The formation of dialkyl (2,5-dialkyl pyrrolidin-2-yl) and dialkyl (5-alkyl pyrrolidin-2-yl)phosphonates was stereoselective and the stereochemistry of diastereomers was assigned using X-ray analysis and ¹H, ¹³C and ³¹P-NMR data. EPR evidence for the production of free radicals during the borohydride reduction of the intermediate organomercurials was achieved by spin-trapping experiments.

Key Words:

• Pyrrolidin-2-yl phosphonates
• aL-aminophosphonates
• aminomercuration
• mercuric acetate
• radical-mediated reduction
• EPR