tert-Butyl (triphenylphosphoranylidene) acetate → 4-(7-methyl-1H-indazol-5-yl)-but-2-enoic Acid Tert-Butyl Ester

Beteiligte Stoffe

Reaktionsschritte

Tetrahydrofuran (8 mL) was added to a flask containing (7-methyl-1H-indazol-5-yl)-acetaldehyde (1.94 mmol, 1.0 equiv) and (tert-butoxycarbonyl-methylene)triphenylphosphorane (1.46 g, 3.88 mmol, 2.0 equiv) at room temperature under nitrogen. The resulting yellow solution was stirred overnight (15 h). LCMS indicated completion. The mixture was partitioned between water and ethyl acetate. The organic layer was separated and washed with brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by flash column chromatography to afford the desired product as a yellow oil (272 mg, 51.5% for two steps). MS (ESI) [M+H]+=273; 1H NMR (400 MHz, CDCl3) δ 12.3 (br., 1H), 8.06 (s, 1H), 7.36 (s, 1H), 7.04 (m, 1H), 6.96 (s, 1H), 5.74 (dd, J=15.6 and 1.6 Hz, 1H), 3.54 (d, J=6.8 Hz; 2H), 2.57 (s, 3H), 1.47 (s, 9H).

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