Aluminum catalyst

A method for producing optically active isopulegol represented by the general formula (8), comprising selectively cyclizing citronellal represented by the general formula (7) using an aluminum catalyst:

• wherein * means an asymmetric carbon atom;
• wherein * means an asymmetric carbon atom,
• wherein the aluminum catalyst is obtained by reacting at least one compound of an alkylaluminum compound represented by the following general formula (1) and a hydridoaluminum compound represented by the following general formula (2) with a hydroxy compound represented by the following general formula (3):
• AlHm(Lg)3-m (1)
• wherein Al is aluminum;
• Lg is a branched, linear or cyclic alkyl group having from 1 to 8 carbon atoms;
• and m is an integer of 0 to 3;
• MAlH4 (2)
• wherein Al is aluminum;
• and M is lithium, sodium or potassium;
• wherein Ar1 is an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, or a heteroaryl group having from 2 to 15 carbon atoms, which optionally has a substituent;
• R1 is a cyclic alkyl group having from 5 to 12 carbon atoms, which optionally has a substituent;
• R2, R3 and R4 each independently are a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, a cyclic alkyl group having from 5 to 12 carbon atoms, a perfluoroalkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, an aralkyl group having from 7 to 12 carbon atoms, which optionally has a substituent, a halogen atom, an organosilyl group, an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, a dialkylamino group having from 2 to 8 carbon atoms, a thioalkoxy group having from 1 to 4 carbon atoms, a nitro group or a polymer chain;
• and R2 and R3, or R3 and R4 are optionally each independently combined with each other to form a condensed benzene ring, a condensed substituted-benzene ring, a trimethylene group, a tetramethylene group, a pentamethylene group, a methylenedioxy group, an ethylenedioxy group or a trimethylenedioxy group.

A method for producing isopulegol represented by the general formula (6), comprising selectively cyclizing citronellal represented by the general formula (5) in the presence of at least one compound of the following compounds I and II using an aluminum catalyst:

• I. at least one acid:
• II. at least one compound selected from the group consisting of an aldehyde other than citronellal, an acid anhydride, a ketone, an acid halide, an epoxy compound and a vinyl ether,
• wherein the aluminum catalyst is obtained by reacting at least one compound of an alkylaluminum compound represented by the following general formula (1) and a hydridoaluminum compound represented by the following general formula (2) with a hydroxy compound represented by the following general formula (3):
• AlHm(Lg)3-m (1)
• wherein Al is aluminum;
• Lg is a branched, linear or cyclic alkyl group having from 1 to 8 carbon atoms;
• and m is an integer of 0 to 3;
• MAlH4 (2)
• wherein Al is aluminum;
• and M is lithium, sodium or potassium;
• wherein Ar1 is an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, or a heteroaryl group having from 2 to 15 carbon atoms, which optionally has a substituent;
• R1 is a cyclic alkyl group having from 5 to 12 carbon atoms, which optionally has a substituent;
• R2, R3 and R4 each independently are a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, a cyclic alkyl group having from 5 to 12 carbon atoms, a perfluoroalkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, an aralkyl group having from 7 to 12 carbon atoms, which optionally has a substituent, a halogen atom, an organosilyl group, an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, a dialkylamino group having from 2 to 8 carbon atoms, a thioalkoxy group having from 1 to 4 carbon atoms, a nitro group or a polymer chain;
• and R2 and R3, or R3 and R4 are optionally each independently combined with each other to form a condensed benzene ring, a condensed substituted-benzene ring, a trimethylene group, a tetramethylene group, a pentamethylene group, a methylenedioxy group, an ethylenedioxy group or a trimethylenedioxy group.

A method for producing optically active isopulegol represented by the general formula (8), comprising selectively cyclizing citronellal represented by the general formula (7) in the presence of at least one compound of the following compounds I and II using an aluminum catalyst:

• I. at least one acid;
• II. at leas(one compound selected from the group consisting of an aldehyde other than citronellal, an acid anhydride, a ketone, an acid halide, an epoxy compound and a vinyl ether,
• wherein * means an asymmetric carbon atom;
• wherein * means an asymmetric carbon atom,
• wherein the aluminum catalyst is obtained by reacting at least one compound of an alkylaluminum compound represented by the following general formula (1) and a hydridoaluminum compound represented by the following general formula (2) with a hydroxy compound represented by the following general formula (3):
• AlHm(Lg)3-m (1)
• wherein Al is aluminum;
• Lg is a branched, linear or cyclic alkyl group having from 1 to 8 carbon atoms;
• and m is an integer of 0 to 3;
• MAlH4 (2)
• wherein Al is aluminum;
• and M is lithium, sodium or potassium;
• wherein Ar1 is an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, or a heteroaryl group having from 2 to 15 carbon atoms, which optionally has a substituent;
• R1 is a cyclic alkyl group having from 5 to 12 carbon atoms, which optionally has a substituent;
• R2, R3 and R4 each independently are a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, a cyclic alkyl group having from 5 to 12 carbon atoms, a perfluoroalkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, an aralkyl group having from 7 to 12 carbon atoms, which optionally has a substituent, a halogen atom, an organosilyl group, an aryl group having from 6 to 15 carbon atoms, which optionally has a substituent, a dialkylamino group having from 2 to 8 carbon atoms, a thioalkoxy group having from 1 to 4 carbon atoms, a nitro group or a polymer chain;
• and R2 and R3, or R3 and R4 are optionally each independently combined with each other to form a condensed benzene ring, a condensed substituted-benzene ring, a trimethylene group, a tetramethylene group, a pentamethylene group, a methylenedioxy group, an ethylenedioxy group or a trimethylenedioxy group.