1H-Pyrrolo(2,3-b)pyridine → 7-aza-1H-indole N-oxide

Participants

Reaction Conditions

Reaction Steps

A solution of 1H-pyrrolo[2,3-b]pyridine (1a) (2.973 kg) in ethyl acetate (22.562 kg) was cooled to 0 to 5° C. To the cooled solution was added a solution of mCPBA (6.872 kg, 1.22 eq) in ethyl acetate (14.884 kg) over the course of about 1.5 h. The residual mCPBA was washed into the reaction mixture by an additional portion of ethyl acetate (5.933 kg). The resulting solution was warmed to 16 to 24° C., and allowed to stir at this temperature until the starting azaindole 1a had been consumed (as judged by reversed phase HPLC analysis). The reaction mixture was then cooled to 0 to 10° C. The resulting slurry was filtered to collect the N-oxide as the meta-chlorobenzoic acid (m-CBA) addition salt 2a′. The solid was washed with additional ethyl acetate and then dried to provide 5.716 kg (78.2%) of 2a′.

Provenance & Evidence