tert-Butanol → HCID 178421551, compound

Participants

Reaction Steps

The pyrrolo[3,2-b]carbazole-2-carboxylic acid (0.86 mmol) and triphenylphosphine (0.91 mmol, 1.05 eq.) were dissolved in freshly distilled tetrahydrofuran under a nitrogen atmosphere. Tertiary butanol (2.12 mmol, 2.5 eq.) was added by syringe, and finally diethyl azodicarboxylate (0.95 mmol, 1.1 eq.) was added dropwise over 10 minutes. The resulting suspension was stirred at room temperature for two hours, by which time TLC showed complete consumption of the starting acid. The title compound was obtained from the crude reaction mixture in several stages: column chromatography on silica, eluting with 20% ether/80% petrol then 50% ether/50% petrol; column chromatography on silica (eluting with 25% ether/75% petrol then 40% ether/60% petrol); and finally, recrystallisation from DCM gave yellow powder (0.030 g, 10%0 m.p. 187°-189° C. (decomp.) (Found: C, 73.24; H, 6.53; N, 7.93. C21H22N2O2.0.15CH2Cl2 requires C, 73.18; H, 6.47; N, 8.07%); δH ([2H6 ]-DMSO) 10.95 (1H, s, 1-NH), 10.57 (1H, s, 5-NH), 8.05 (1H, d, J 8, 9-H), 7.88 (1H, s, 10-H), 7.29-7.43 (2H, m, 6-H, 7-H), 7.05 (1H, ddd, J 8, 6, 1, 8-H), 2.89 and 2.87 (2×3H, 2×s, 3-CH3 and 4-CH3) and 1.59 (9H, s, C(CH3)3); m/z (%) 355(62, M+1+), 278(90), 233(38), 126(32), 91(78) and 57(100); νmax (KBr Disc)/cm-1 3337, 1664 and 1240.

Provenance & Evidence