反应详情

To a solution of (1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-3a-isocyanato-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)octadecahydro-1H-cyclopenta[a]chrysen-9(5bH)-one (2.1 g, 4.65 mmol) in dioxane (30 mL) at RT was added 7 mL conc. HCl over a period of 5 minutes. The clear solution was stirred for 10 minutes, forming a slightly turbid mixture. Stirring continued for a total of 6 hours and the reaction mixture turned into a 2-layer mixture. All the volatile solvents were removed under high vacuum. The dried, crude material was dissolved into DCM (15 mL), poured over a short bed (˜1″ thick) of silica gel type-H, washed with 500 mL, 20% ethyl acetate in hexanes, followed by a 2:1 mixture of DCM:Ethyl acetate (0.5 L). Upon concentration, a pale gum was obtained. The material was dried under high vacuum to give 1.55 gm (72% yield). MS: m/e 426.40 M+, 4.11 min (method 11). 1H NMR (400 MHz, CHLOROFORM-d) δ 8.24 (br. s., 3H), 4.83 (br. s., 1H), 4.66 (br. s., 1H), 2.62-2.17 (m, 4H), 2.16-1.78 (m, 5H), 1.77-1.31 (m, 17H), 1.30-1.16 (m, 5H), 1.09 (s, 3H), 1.03 (s, 3H), 0.99 (br. s., 3H), 0.93 (s, 3H).

1. customforming a slightly turbid mixture
2. stirringStirring
3. customcontinued for a total of 6 hours
4. customAll the volatile solvents were removed under high vacuum
5. dissolutionThe dried, crude material was dissolved into DCM (15 mL)
6. additionpoured over a short bed (˜1″ thick) of silica gel type-H
7. washwashed with 500 mL, 20% ethyl acetate in hexanes
8. additionfollowed by a 2:1 mixture of DCM
9. concentrationUpon concentration
10. customa pale gum was obtained
11. customThe material was dried under high vacuum
12. customto give 1.55 gm (72% yield)
13. custom4.11 min (method 11)