反应详情

The reaction was charged with 1-tert-butyl 4-((3aR,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-formyl-1-isopropyl-5a,5b,8,8,11a-pentamethyl-2-oxo-3,3a,4,5,5a,5b,6,7,7a,8,9,10,11,11a,11b,12,13,13a-octadecahydro-2H-cyclopenta[a]chrysen-9-yl) 2,2-dimethylsuccinate (15.75 g, 1 equiv), tert-butanol (157 ml, 10 vol) and toluene (47 ml, 3 vol) and stirred at ambient temperature. The ligand (N1,N2-bis(1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl)ethane-1,2-diamine, derived from (S)-camphor, 0.492 g, 0.06 equiv) and copper (II) acetate mono hydrate (0.246 g, 0.05 equiv) were added in a single portion and reaction allowed to stir at ambient temperature for at least 2.5 hours (see note 1). The reaction is charged with nitromethane (7.52 g, 5 equiv) and Hunig's base (“N,N-diisopropylethylamine”-3.82 g, 1.2 equiv) and allowed to stir at ambient temperature for approximately 5 days. (See note 2). Reaction concentrated under vacuum at bath temp of no more than 35° C. to approximately 2 vols. (See note 3). Reaction charged with toluene (236 ml, 15 vols) and concentrated under vacuum again to approx 3 vols. Additional toluene (95 ml, 3 vol) was added to achieve a final reaction volume of approx 6 vols. Heptane (158 ml, 10 vols) was added slowly of to solution. Product began to crystallize out of solution upon seeding. Reaction was allowed to stir at ambient temperature for one to two hours and solids collected by filtration and washed with 10 vols of heptane. Solids were dried to a weight of 14.3 g (83% yield). Purity of isolated solid is typically ˜90-95% with a 98/2 diastereomeric ratio favoring 1-tert-butyl 4-((3aR,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-((R)-1-hydroxy-2-nitroethyl)-1-isopropyl-5a,5b,8,8,11a-pentamethyl-2-oxo-3,3a,4,5,5a,5b,6,7,7a,8,9,10,11,11a,11b,12,13,13a-octadecahydro-2H-cyclopenta[a]chrysen-9-yl) 2,2-dimethylsuccinate as the major diastereomer.

1. stirringto stir at ambient temperature for at least 2.5 hours (see note 1)
2. stirringto stir at ambient temperature for approximately 5 days
3. customReaction
4. concentrationconcentrated under vacuum at bath temp of no more than 35° C. to approximately 2 vols
5. customReaction
6. concentrationconcentrated under vacuum again
7. additionAdditional toluene (95 ml, 3 vol) was added
8. customreaction volume of approx 6 vols
9. customto crystallize out of solution
10. customReaction
11. stirringto stir at ambient temperature for one to two hours
12. filtrationsolids collected by filtration
13. washwashed with 10 vols of heptane
14. customSolids were dried to a weight of 14.3 g (83% yield)