Nitrones and Oxaziridines. XXIV. Preparation and Reactions of 3-Bromo-2-cyano-1-pyrroline 1-Oxides: Formation of 2-Cyano-3-oxo-1-pyrroline 1-Oxides and 5-Cyano-2H-pyrrole 1-Oxides

2-Cyano-1-pyrroline 1-oxides (1) have been brominated using N -bromosuccinimide and the resulting 3-bromo-2-cyano-1-pyrroline I-oxides (2) have been further transformed into (i) 2-cyano-1-pyrrolin- 3-yl nitrate 1-oxides (3) by treatment with silver nitrate, (ii) 2-cyano-3-hydroxy-1-pyrroline 1-oxides (4) by treatment with sodium bicarbonate, and (iii) 5-cyano-2H-pyrrole 1-oxides (8) by treatment with either pyridine N -oxide or triethylamine. The 2-cyano-3-oxo-1-pyrroline 1-oxides (5) were prepared by reaction of the nitrate esters (3) with triethylamine.