[C:1]1([N:7]2[C:15](=[O:16])[C:14]3[C@@H:13]4[C:17]([CH3:19])([CH3:18])[C@@:10]([CH3:20])([CH2:11][CH2:12]4)[C:9]=3[NH:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[CH3:21]I>CN(C)C=O>[C:1]1([N:7]2[C:15](=[O:16])[C:14]3[C@@H:13]4[C:17]([CH3:19])([CH3:18])[C@@:10]([CH3:20])([CH2:11][CH2:12]4)[C:9]=3[N:8]2[CH3:21])[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1A mixture of (4S,7R)-2-phenyl-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (Intermediate 6; 4.77 g, 17.8 mmol) and methyl iodide (2.2 mL, 35.3 mmol) in N,N-dimethylformamide (30 mL) was purged with argon and then heated in a sealed tube at 100° C. overnight. The reaction mixture was cooled to room temperature, diluted with sodium bicarbonate and extracted three times with ethyl acetate. The combined organic extracts were washed with water and brine, dried (magnesium sulfate), filtered, evaporated and purified using an Analogix Intelliflash 280 system (Analogix, Inc., Burlington, Wis.) with an Analytical Sales 120 g column, eluting with 25-75% ethyl acetate/hexanes followed by recrystallization from ethyl acetate to give (4S,7R)-2-phenyl-1,7,8,8-tetramethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (2.8 g) of white crystals. The filtrate was evaporated and recrystallized from ethyl acetate to give a further 0.53 g, and the resulting filtrate was evaporated, dissolved in dichloromethane, treated with decolorizing charcoal and crystallized from dichloromethane to give a further 0.77 g of product. The total yield was 4.1 g (82%). EI(+)-MS (M+H) 283.
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