58% |
With sodium tetrahydroborate In tetrahydrofuran; methanol Reflux; |
161.2 Example 161: 4-chloro-N-(4-chlorophenyl)-1-cyclohexyl-3-methyl-1H-pyrazolo [3,4-b]pyridine-5-carboxamide
General procedure: To a solution of tert-butyl 2-cyclohexylidenehydrazine-1-carboxylate (crode, 15.1 mmol) in THF/MeOH (1/1, 50 mL) was added NaBH4 (2.8 g, 75.5 mmol), it was then refluxed overnight. Resultant was evaporated to remove solvent, then residue was diluted with EA (100 mL) and quenched by water (100 mL), organic layer was concentrated to afford 1.9 g (yield: 58%) of tert-butyl 2-cyclohexylhydrazine-1-carboxylate as colorless oil.‘HNMR (300 MHz, DMSO-d6): = 8.15 (s, 1H), 4.11 (s, 1H), 2.65-2.58 (m, 1H), 1.70-1.66 (m, 5H), 1.41 (s, 9H), 1.19-0.93 (m, 5H); |
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With hydrogen In ethanol |
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With borane-THF In tetrahydrofuran for 0.166667h; Ambient temperature; |
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With borane In tetrahydrofuran at 20℃; for 0.333333h; |
177.A
To a solution of cyclohexanone (1.25 mL) in hexanes (8 mL) was added 1.59 g of tert-butyl carbazate. The mixture was heated at reflux for 10 min and then allowed to cool to RT. The white precipitate that had formed was removed by filtration and washed with cold hexanes. The white solid was then treated with BH3 (1. 0 M in THF, 12 mL). After stirring at RT for 20 min, the mixture was treated with 16 mL of 6 N HCI. The mixture was heated at 110°C for 20 min and then was concentrated in vacuo. The residue was treated with 30 mL of THF. The title compound (1.82 g), a white solid, was collected from this mixture by filtration. MS (ESI) : exact mass calculated for C6H14N2, 114.12 ; found, mlz 115. 1 [M+H] +. 1H NMR (500 MHz, CDC13) : 3.05-2. 99 (m, 1H), 2.11-2. 09 (m, 2H), 1.88-1. 86 (m, 2H), 1.72-1. 69 (m, 1H), 1.37-1. 19 (m, 5H). |
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Stage #1: tert-butyl 2-cyclohexylidenehydrazine-1-carboxylate With sodium cyanoborohydride; acetic acid In methanol at 20℃; for 16h;
Stage #2: With sodium hydroxide; water In methanol at 0℃; |
The intermediate imine was dissolved in MeOH (30 mL) and sodium cyanoborohydride (ALDRICH, 45.9 mmol) and glacial acetic acid (8.2 mL, 143.2 mmol) were added. After stirring the resulting reaction mixture at room temperature for 16h, it was cooled down to 0 °C and neutralised with 2N aq. NaOH (8.2 mL). The organic solvent was evaporated under vacuum and product was extracted with DCM. The combined organic layers were washed with brine and dried over anhydrous Na2SO4, yielding the above title compound. 1H NMR (300 MHz, CDCl3) δ ppm: 2.90- 2.76 (m, 1H), 1.94- 1.8 (m, 2H), 1.79- 1.7 (m, 2H), 1.67- 1.57 (m, 1H), 1.54- 1.42 (br., 9H), 1.40- 1.02 (br. m, 6H). |
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With borane-THF In tetrahydrofuran at 40 - 60℃; for 1h; |
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