反应详情

To a 500-mL 3-neck round-bottomed flask was added (1S,2R)-ethyl 2-methyl-4-oxocyclohexanecarboxylate (10.00 g, 54.3 mmol) in chloroform (201 ml). Then AcOH, glacial (3.13 ml, 54.3 mmol), and tert-butyl carbazate (7.89 g, 59.7 mmol) was added into the reaction mixture. The flask was placed into a pre-heated bath (30° C.) and allowed to stir 10 min. Then NaBH(OAc)3 (34.5 g, 163 mmol) was slowly added into the reaction mixture in small portions. The bath was removed after the addition and the overall mixture was allowed to stir under inert atmosphere 16 h. The progress of the reaction was monitored by LC/MS and TLC (30% EtOAc/DCM; Ninhydrin stain) which suggested reaction completion. The mixture was neutralized with the slow addition of sat. aq. NaHCO3 into the reaction mixture. After the material was neutralized, the layers were separated and the aqueous layer was extracted with DCM (3×). The combined organic extracts were dried over Na2SO4, filtered and concentrated in-vacuo. The crude sample was analyzed by TLC (30% EtOAc/hexane; ninhydrin stain; Peak 1: Rf=0.46 & Peak 2: Rf=0.38) The crude material was divided into two portions and purified by chromatography through an Interchim (25 micron) silica-gel column (300 g)*(Two 300 Gram Columns were used), eluting with a gradient of 0-30% EtOAc in hexane, to provide tert-butyl 2-((1R,3R,4S)-4-(ethoxycarbonyl)-3-methylcyclohexyl)hydrazinecarboxylate (8.512 g, 28.3 mmol, 52.2% yield) (Peak 1; Cis)1H NMR (400 MHz, CDCl3) δ 6.03-6.28 (m, 1H), 4.07-4.16 (m, 2H), 3.59-3.90 (m, 1H), 2.76-2.97 (m, 1H), 2.55 (d, J=2.74 Hz, 1H), 2.01 (dd, J=3.03, 13.40 Hz, 1H), 1.59-1.77 (m, 3H), 1.49-1.56 (m, 2H), 1.46 (s, 10H), 1.19-1.31 (m, 3H), 1.02 (d, J=7.04 Hz, 3H); LCMS (ESI) m/z 301.1 (M+H)+ and tert-butyl 2-((1S,3R,4S)-4-(ethoxycarbonyl)-3-methylcyclohexyl)hydrazinecarboxylate (5.089 g, 16.94 mmol, 31.2% yield) (Peak 2; trans)1H NMR (400 MHz, DMSO-d6) δ 7.89-8.27 (m, 1H), 5.75 (s, 1H), 4.08-4.19 (m, 1H), 2.74-2.93 (m, 1H), 2.21-2.46 (m, 2H), 1.99 (s, 1H), 1.66 (d, J=3.91 Hz, 3H), 1.38 (s, 9H), 1.14-1.26 (m, 5H), 0.79 (d, J=7.04 Hz, 3H); LCMS (ESI) m/z 301.1 (M+H)+.

1. customThe flask was placed into a pre-heated bath
2. custom(30° C.)
3. customThe bath was removed
4. additionafter the addition
5. stirringto stir under inert atmosphere 16 h
6. customreaction completion
7. customthe layers were separated
8. extractionthe aqueous layer was extracted with DCM (3×)
9. dry with materialThe combined organic extracts were dried over Na2SO4
10. filtrationfiltered
11. concentrationconcentrated in-vacuo
12. custompurified by chromatography through an Interchim (25 micron) silica-gel column (300 g)
13. washeluting with a gradient of 0-30% EtOAc in hexane