tert-butyl 4-chlorobenzyl(2-((3aR,5aR,5bR,7aR,9S,11aR,11bR,13aS)-9-hydroxy-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-3a-yl)-2-oxoethyl)carbamate 、
4-叔丁氧基-3,3-二甲基-4-氧代丁酸 在
4-叔丁氧基-3,3-二甲基-4-氧代丁酸 作用下,
以71.4的产率得到4-((3aR,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-(N-(tert-butoxycarbonyl)-N-(4-chlorobenzyl)glycyl)-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) 1-(tert-butyl) 2,2-dimet