Triethylamine → (2S)-ethyl 2-tert-butoxy-2-(7-(8-fluoro-5-methylchroman-6-yl)-5-methyl-2-((2-(trimethylsilyl)ethoxy)carbonylamino)pyrazolo[1,5-a]pyrimidin-6-yl)acetate

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A mixture of 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(8-fluoro-5-methylchroman-6-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylic acid (3.40 g, 5.79 mmol), diphenylphosphoryl azide (1.50 mL, 6.94 mmol), 2-(trimethylsilyl)ethanol (1.66 mL, 11.6 mmol), triethylamine (0.968 mL, 6.94 mmol) in toluene (100 mL) was refluxed for 16 h. It was then concentrated in vacuo. The residue was purified by biotage eluting with 20% EtOAc/hexane to isolate 2.5 g (70%) of (2S)-ethyl 2-tert-butoxy-2-(7-(8-fluoro-5-methylchroman-6-yl)-5-methyl-2-((2-(trimethylsilyl)ethoxy)carbonylamino)pyrazolo[1,5-a]pyrimidin-6-yl)acetate as off-white solid. 1H NMR (500 MHz, CDCl3) δ 7.25 (s, 1H), 6.89 (s, 1H), 6.87 (d, J=6.9 Hz, 1H), 4.90 (s, 1H), 4.34 (m, 2H), 4.30 (m, 2H), 4.13 (d, J=7.1 Hz, 2H), 2.84-2.63 (m, 5H), 2.18 (m, 2H), 1.84 (s, 3H), 1.20 (t, J=7.1 Hz, 3H), 1.17 (s, 9H), 1.05 (m, 2H), 0.07 (s, 9H). LCMS (M+H)=615.4.

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