Phosphoric Acid → ethyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(aziridin-1-yl)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)cyclohex-3-enecarboxylate

Participants

Reaction Conditions

Reaction Steps

To a sealable vial was added ethyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-amino-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)cyclohex-3-enecarboxylate (0.1 g, 0.178 mmol), 1-bromo-2-chloroethane (0.148 mL, 1.780 mmol) and phosphoric acid, potassium salt (0.189 g, 0.890 mmol). The mixture was diluted with acetonitrile (1.5 mL), was flushed with nitrogen, then was sealed and heated to 120° C. After 17.5 h of heating, the mixture was cooled to rt and some of the solids were removed by filtration. The filtrate was concentrated under reduced pressure to give ethyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(aziridin-1-yl)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)cyclohex-3-enecarboxylate as the crude product which was used in the next step with no additional purification. LCMS: m/e 588.7 (M+H)+, 2.30 min (method 1).

Provenance & Evidence