(3,3,3-Trifluoropropyl)hydrazine dihydrochloride → 3-((tert-butyldimethylsilyloxy)methyl)-2-(1-(3,3,3-trifluoropropyl)-1H-pyrazol-5-yl)pyridine

Participants

Reaction Conditions

Reaction Steps

To (E)-1-(3-((tert-butyldimethylsilyloxy)methyl)pyridin-2-yl)-3-(dimethylamino)prop-2-en-1-one (crude above, 1.73 g, 5.41 mmol, 1 eq.) in EtOH (10 mL) was added (3,3,3-trifluoropropyl)hydrazine dihydrochloride (1.30 g, crude above, 6.49 mmol, 1.2 eq.) at RT. The mixture was heated at 80° C. for 1 h, concentrated, and diluted with EtOAc (50 mL) and NaHCO3(sat) solution (10 mL). The layers were separated and aqueous layer was extracted with EtOAc three times. The combined organic layers were dried over Na2SO4, concentrated, and purified on silica gel using a mixture of EtOAc and hexanes as eluent to give 3-((tert-butyldimethylsilyloxy)methyl)-2-(1-(3,3,3-trifluoropropyl)-1H-pyrazol-5-yl)pyridine (1.58 g; 76% for 2 steps). 1H NMR (400 MHz, CDCl3) δ 8.53 (dd, J=4.7, 1.6 Hz, 1H), 7.96-7.88 (m, 1H), 7.51 (d, J=1.9 Hz, 1H), 7.29 (dd, J=7.9, 4.7 Hz, 1H), 6.34 (d, J=1.9 Hz, 1H), 4.62 (s, 2H), 4.45-4.33 (m, 2H), 2.82-2.61 (m, 2H), 0.85 (s, 8H), −0.00 (s, 5H). MS (ESI) m/z 386.2 [M+H]+.

Provenance & Evidence