反应详情

Sodium triacetoxyborohydride (14.5 g, 68.7 mmol) was added to a solution of 2,3-diaminopyridine (5.00 g, 45.8 mmol) and N-(t-butoxycarbonyl)-4-piperidone (9.58 g, 48.1 mmol) in dichloroethane (75 mL) at room temperature. After 5 h, additional sodium triacetoxyborohydride was added (1.8 g) and again after another 2.5 h. The reaction was stirred overnight, and quenched with 5% aqueous sodium hydroxide. This was extracted with methylene chloride, and washed with 5% aqueous sodium hydroxide, water and saturated sodium chloride solution. After drying over sodium sulfate, the solution was filtered and evaporated to give the crude product. This was purified by chromatorgraphy (silica gel, 3 to 5% methanol in methylene chloride gradient elution), which gave the title compound (4.44 g). MS 293 (M+1) 1H NMR (500 MHz, CD3OD) δ 7.32 (dd, J=1, 5 Hz, 1H), 6.85 (dd, J=1, 8 Hz, 1H), 6.59 (dd, J=5, 8 Hz, 1H), 4.04 (d, J=13 Hz, 2H), 3.46 (m, 1H), 2.98 (br s, 2H), 2.01 (dd, J=2, 12 Hz, 2H), 1.46 (s, 9H), 1.37 (qd, J=4, 12 Hz, 2H).

1. waitagain after another 2.5 h
2. customquenched with 5% aqueous sodium hydroxide
3. extractionThis was extracted with methylene chloride
4. washwashed with 5% aqueous sodium hydroxide, water and saturated sodium chloride solution
5. dry with materialAfter drying over sodium sulfate
6. filtrationthe solution was filtered
7. customevaporated
8. customto give the crude product
9. customThis was purified by chromatorgraphy (silica gel, 3 to 5% methanol in methylene chloride gradient elution), which