Trimethylsilylacetylene → 8-Trimethylsilylacetylenyl-1-methyl-6-phenyl-4H-s-triazolo[4,3-a][1,4]-benzodiazepine

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Reaction Steps

(XLi269). A mixture of 8 (8-bromo-1-methyl-6-phenyl-4-H-s-triazolo-[4,3-a][1,4]benzodiazepine, 300 mg, 0.85 mmol), trimethylsilylacetylene (208.5 mg, 2.12 mmol) and bis(triphenylphosphine)-palladium(II) acetate in a mixed solvent system of EtN3 (5 mL) and CH3CN (8mL) was heated to reflux under nitrogen. See, Liu, et al., 1996; Austin, et al., 1981; Heck, 1985. After stirring for 6 hours at reflux, the mixture was cooled to room temperature. The mixture was concentrated under reduced pressure and H2O (30 mL) was added. The mixture was extracted with CH2Cl2 (3×50 mL). The combined extracts were washed with brine and dried (Na2SO4). After removal of solvent under reduced pressure, the residue was purified by flash chromatography (silica gel, EtOH/EtOAc) to afford benzodiazepine 9 (185 mg, 60% yield) as a white solid: mp 229-233° C.; IR (KBr) 2957, 2156, 1609, 1537, 1491, 1424, 1315, 1249, 881, 844, 750 cm−1; 1H NMR (CDCl3) δ 0.23 (s, 9H), 2.68 (s, 3H), 4.11 (d, 1H, J=12.5Hz), 5.49 (d, 1H, J=13.0Hz), 7.21-7.68(m,7H), 7.75(dd, 1H, J=8.5Hz, J=1.5Hz); MS (EI) m/e (relative intensity) 370 (M+, 80), 355 (44), 341 (60), 286 (34), 177 (51), 163 (52) 143 (100), 129 (19), 115 (28). Anal. Calcd. for C22H22N4Si: C, 71.31; H, 5.98; N, 15.12. Found: C, 70.90; H, 5.93; N, 15.08.

Provenance & Evidence