Triethylamine → 1H,2H,3H-pyrrolo(2,3-b)pyridine

Participants

Reaction Steps

98% Formic acid (37.5 mL, 0.97 mol) was added to a stirred and cooled (ice bath) neat Et3N (150 mL, 1.08 mol). A two-phase system, which was formed, was then added to a mixture of 7-azaindole (50.0 g, 0.424 mol), formic acid (750 mL), and 10% palladium on activated carbon (26.75 g, Degussa type), and stirred at 80° C. for 4 d. The mixture was cooled to r.t., the catalyst was filtered off and washed with formic acid (100 mL). The filtrate and washings were combined and concentrated in vacuum. The residual liquid was cooled (ice bath) and basified to pH 13 by slow addition of 50% aqueous NaOH (total of about 500 mL). Then, the mixture was refluxed for 2 h until TLC showed completion. Ice was added in amount sufficient to lower the temperature of the mixture to 20° C. The two-phase system was then extracted with AcOEt (5×500 mL). Combined extracts were washed with brine, dried MgSO4, and concentrated in vacuum. The residual brown solid was separated by means of SGC with AcOEt:MeOH as eluent to afford recovered 1 (12.57 g, 25%) and desired 2 (36.05 g, 71%). 1H NMR (400 MHz, CDCl3) δ 3.05 (t, J=8.4 Hz, 2H), 3.60 (t, J=8.4 Hz, 2H), 4.52 (bs, 1H), 6.49 (dd, J=7.0, 5.3 Hz, 1H), 7.23 (dq, J=7.0, 1.3 Hz, 1H), 7.81 (ddt, J=5.3, 1.3, 1.1 Hz, 1H).

Provenance & Evidence