of m-chloroperbenzoic acid (83.0%, 78.8 mg, 0.379 m o l ) in 3 mL of CHC1, was pipetted into a stirred solution of 4-methoxy-4'nitro-2,2'-bipyridyl(24,21.9 mg, 0.0947 mmol) in 3 mL of CHC13 at 0 OC. The reaction was allowed to stir at room temperature for 45 h. The solution was placed on a 5.0-g basic alumina column and eluted with 250 mL of CHC13, 100 mL of 191 CHC13:MeOH, and 50 mL of 9:l CHC1,:MeOH. The combined filtrates were evaporated, providing 24.6 mg of solid. This was placed on a 500-rm silica gel prep plate with CHCl, and developed with 9:l CHC1,:MeOH. Three UV-active bands were seen and were removed with 19:l CHC1,:MeOH. The top band yielded 1.6 mg (0.0069 mmol) of 4-methoxy-4'-nitro-2,2'-bipyridyl (24), mp 135 "C. The middle band gave 16.0 mg (0.0647 mmol) of 4-methoxy-4'-nitro-2,2'-bipyridyl N-oxide (22,68.3% conversion of 24 or 73.3% based on recovered 24), mp 177-178 "C. The bottom band gave 0.1 mg (0.0004 mmol) of 4-methoxy-4'-nitro-2,2'-bipyridyl N,"-dioxide (19,0.4% conversion of 24 or 0.4% based on recovered 24), mp 225-230 "C (mp of the dioxide prepared from 3 was 236 "C, mixed mp 225-230 "C; IR and TLC properties also identical).
4-Methoxy-4'-nitro-2,2/-bipyridyl (24). Phosphorus trichloride (0.200 mL, 2.29 "01)
was syringed into a stirred solution of 4-methoxy-4'-nitro-2,2'-bipyridyl N-oxide (22, 100 mg, 0.405 mmol) in 7 mL of CHCl,. Within a few seconds the yellow color of the solution had disappeared. The reaction was refluxed for 4.25 h and allowed to stand at room temperature overnight. The reaction was worked up with use of the procedure described in the preparation of 10 providing 92.5 mg of 4-methoxy-4'-nitro-2,2'-bipyridyl (24): mp 136 "C (98.9% yield); 'H NMR (CDC13)