Trimethylsilylacetylene → 4-Methyl-6-phenyl-8-trimethylsilanylethynyl-4H-2,5,10b-triaza-benzo[e]azulene-3-carboxylic acid ethyl ester

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A mixture of ester 112 (3.0 g, 7.07 mmol) and bis(triphenylphosphine)palladium (II) acetate (0.42 g, 0.57 mmol) was dissolved in a mixed solvent system of acetonitrile (80 mL) and TEA (120 mL). The mixture was degassed under vacuum and argon gas was added, after which trimethylsilylacetylene (2 mL, 14.14 mmol) was added into the mixture. The mixture was degassed again under vacuum (argon) and heated to reflux. The mixture was heated at reflux until analysis by TLC (EtOAc) indicated that all of the starting material 112 had been consumed. The mixture was cooled to rt and the precipitate which formed was removed by filtration through celite. The filtrate was concentrated under reduced pressure and partitioned between H2O and EtOAc. The combined layers of EtOAc were washed with brine and dried (Na2SO4), after which the solvent was removed under reduced pressure and the residue was purified by flash chromatography (silica gel, EtOAc:hexane 1:1). Conditions for TLC were EtOAc. A white solid 113 (2.60 g, 83.3%) was obtained. mp 160-162° C.; IR (KBr, cm−1) 3365, 2925, 1706, 1616, 1553, 1498; 1H NMR (CDCl3) δ 7.89 (s, 1 H), 7.73 (dd, J=1.73 Hz, 1 H), 7.51-7.36 (m, 7 H), 6.66 (q, J=7.30, 1 H), 4.45-4.30 (m, 2 H), 1.40 (t, J=7.11, 3 H), 1.25 (d, J=7.38 Hz, 3 H), 0.15 (s, 9 H). MS (EI) m/e (relative intensity) 441 (M+, 15), 369 (25), 323 (55), 295 (100), 267 (15).

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