Process for producing pyripyropene derivatives and intermediates for the production thereof

1. 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.

2. The process according to claim 1 , further comprising, before acylation of hydroxyl at the 1- and 11-positions of compound Fb, the steps of:

hydrolyzing acyl at the 1-, 7-, and 11-positions of compound A4 represented by formula A4:

wherein A 1 , A 7 , and A 11 , which may be the same or different, represent acetyl or propionyl,

with a base to deacylate compound A4, then protecting hydroxyl at the 1- and 11-positions to give compound D represented by formula D:

wherein two R 2 s together represent a group selected from groups represented by formulae D-1, D-2, D-3, and D-4:

wherein Y 1 represents a hydrogen atom or C 1-4 alkyl; Xs, which may be the same or different, represent a hydrogen atom, C 1-4 alkoxy, or nitro; and n is 0 to 5,

then protecting hydroxyl at the 7-position of compound D to give compound E represented by formula E:

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 substitutent 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, and

R 2 is as defined above,

and further removing the protective groups at the 1- and 11-positions of compound E to give compound Fb represented by formula Fb:

wherein R 1b is as defined above.

3. The process according to claim 2 , wherein R 1b represents acetyl; chloroacetyl; or 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, and

wherein two R 2 S together represent a group represented by formula D-1 or D-2:

wherein Y 1 represents a hydrogen atom or C 1-4 alkyl; Xs, which may be the same or different, represent a hydrogen atom, C 1-4 alkoxy, or nitro; and n is 0 to 5.