1,1,3,3-Tetramethylguanidine → Methyl-2-(tert-butoxycarbonyl)-3-(7-methyl-2-[{2-[trimethylsilyl]ethoxy}methyl]-2H-indazol-5-yl)acrylate

Participants

Reaction Steps

To a stirred solution of 7-methyl-2-((2-(trimethylsilyl)ethoxy)methyl)-2-H-indazole-5-carbaldehyde (8.5 g, 29.3 mmol) and methyl-2-(tert-butoxycarbonyl)-2-(dimethoxyphosphoryl)acetate (10 g, 32.2 mmol, 1.1 equiv) in tetrahydrofuran (30 mL) at 0° C. was added tetramethylguanidine (5.9 mL, 49.8 mmol, 1.7 equiv). After 10 min, the ice bath was removed and the reaction stirred at room temperature overnight. The solvent was evaporated and the residue purified by flash chromatography on silica gel to afford 11.2 g (83%). 1H-NMR (CD3OD, 300 MHz) δ −0.05 (s, 9H), 0.84-0.96 (m, 2H), 1.14 (bs, 9H), 2.56 (s, 3H), 3.58-3.70 (m, 2H), 3.82 (s, 3H), 5.73 (s, 2H), 7.41 (s, 1H), 7.45 (s, 1H), 7.84 (s, 1H), 8.41 (s, 1H). Mass spec.: 462.5 (MH)+.

Provenance & Evidence