Reacción #172945

Ecuación de reacción

PCC

tert-butyl ((1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysen-3a-yl)carbamate

pyridinium chlorochromate

→

tert-butyl ((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]chrysen-3a-yl)carbamate

Disolventes

dichloromethane

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.STIRRINGthe mixture was stirred at rt for 1 h
2. 2
   FiltraciónThe mixture was filtered through a plug of silica gel and celite which
3. 3
   Lavadowas washed with a solution of 25% ethyl acetate in hexanes
4. 4
   ConcentraciónThe filtrate was concentrated under reduced pressure

Procedimiento

To a solution of the resulting tert-butyl ((1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysen-3a-yl)carbamate in dichloromethane (100 mL) was added pyridinium chlorochromate (4.69 g, 21.74 mmol). The mixture was stirred at rt for 5 h then an additional 1.0 g of PCC was added and the mixture was stirred at rt for 1 h. The mixture was filtered through a plug of silica gel and celite which was washed with a solution of 25% ethyl acetate in hexanes. The filtrate was concentrated under reduced pressure to give tert-butyl ((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]chrysen-3a-yl)carbamate as a light-yellow foam. 1H NMR (500 MHz, CHLOROFORM-d) δ=4.74 (d, J=1.7 Hz, 1H), 4.63 (t, J=1.7 Hz, 1H), 4.34 (br. s., 1H), 2.65-2.34 (m, 5H), 2.05-1.88 (m, 2H), 1.71 (s, 3H), 1.47 (s, 9H), 1.10 (s, 3H), 1.08 (s, 3H), 1.05 (s, 3H), 0.99 (s, 3H), 0.96 (s, 3H), 1.76-0.93 (m, 18H).

Fuente