反应详情

To a solution of (1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-9-oxo-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carboxylic acid (2.1 g, 4.62 mmol) in dioxane (20 mL) was added diphenylphosphoryl azide (DPPA 1.294 mL, 6.00 mmol) and N,N-diisopropylethylamine (2.092 mL, 12.01 mmol) forming a clear solution. The mixture was stirred at RT for 40 minutes before it was immersed into an oil bath at 102° C. under a nitrogen atmosphere for 16 hrs. The crude mixture was evaporated to dryness, re-dissolved into 100 mL DCM, washed 3 times with water. The product was purified by silica gel chromatography eluted with mixture of 20% ethyl acetate in hexanes to give 1.91 gm (92% yield) of the title product. MS: m/e 452.35 (M+H)+, 5.58 min (method 10). 1H NMR (400 MHz, CHLOROFORM-d) δ 4.76 (d, J=2.0 Hz, 1H), 4.66-4.64 (m, 1H), 2.60-2.47 (m, 2H), 2.43 (dd, J=7.5, 4.5 Hz, 1H), 2.11 (br. s., 1H), 1.96-1.77 (m, 5H), 1.76-1.70 (m, 1H), 1.69 (d, J=0.5 Hz, 3H), 1.64-1.42 (m, 10H), 1.42-1.29 (m, 4H), 1.23-1.15 (m, 1H), 1.10 (s, 3H), 1.09 (s, 3H), 1.04 (s, 3H), 0.96 (s, 6H).

1. customforming a clear solution
2. waitwas immersed into an oil bath at 102° C. under a nitrogen atmosphere for 16 hrs
3. customThe crude mixture was evaporated to dryness
4. dissolutionre-dissolved into 100 mL DCM
5. washwashed 3 times with water
6. customThe product was purified by silica gel chromatography
7. washeluted with mixture of 20% ethyl acetate in hexanes