Patent ID: 8263778

Claim:
A process for producing compound C represented by formula C: wherein R′ represents cyclic C 3-6 alkylcarbonyl, the process comprising: acylating hydroxyl at the 1- and 11-positions of compound Fb represented by formula Fb: wherein R 1b represents formyl; optionally substituted straight chain C 1-4 alkylcarbonyl; optionally substituted benzyl; group —SiR 3 R 4 R 5 optionally substituted by halogen atom wherein R 3 , R 4 , and R 5 each independently represent straight chain or branched chain C 1-6 alkyl or phenyl; C 1-6 alkyloxy-C 1-6 alkyl optionally substituted by halogen atom; C 1-6 alkylthio-C 1-6 alkyl optionally substituted by halogen atom; straight chain, branched chain, or cyclic C 1-4 alkyl optionally substituted by halogen atom, provided that, when alkyl in the C 1-4 alkyl group is of a branched chain or cyclic type, the alkyl group is C 3-4 alkyl; C 2-6 alkenyl optionally substituted by halogen atom; C 2-6 alkynyl optionally substituted by halogen atom; or an optionally substituted saturated or unsaturated five- or six-membered heterocyclic group, wherein, in R 1b , the substituent optionally possessed by alkylcarbonyl is selected from the group consisting of halogen atoms, C 1-4 alkyloxy, C 1-4 haloalkyloxy, C 1-4 alkylcarbonyl, C 1-4 haloalkylcarbonyl, C 1-4 alkylcarbonyloxy, and C 1-4 haloalkylcarbonyloxy, and the substituent optionally possessed by the heterocyclic group and benzyl is selected from the group consisting of halogen atoms, C 1-4 alkyl, C 1-4 alkyloxy, C 1-4 haloalkyloxy, C 1-4 alkylthio, C 1-4 haloalkyl, C 1-4 alkylcarbonyl, C 1-4 haloalkylcarbonyl, C 1-4 alkylcarbonyloxy, C 1-4 haloalkylcarbonyloxy, nitro, and cyano, with an acylating agent corresponding to R′ as defined above to give compound B2b represented by formula B2b: wherein R 1b and R′ are as defined above, and then removing R 1b of compound B2b to produce compound C.