Titanium compound and process for producing optically active cyanohydrins

A process for producing optically active cyanohydrins, which comprises reacting aldehyde or unsymmetrical ketone with a cyanating agent in the presence of a titanium compound produced from a partial hydrolysate of a titanium tetraalkoxide compound and an optically active ligand represented by the general formula (b), or a titanium oxoalkoxide compound represented by the general formula (a) and an optically active ligand represented by the general formula (b),

• [TixOy](OR1)4x−2y (a)
• wherein, in the formula, R1 is an alkyl group or an aryl group, each of which may have a substituent;
• x is an integer of not less than 2;
• y is an integer of not less than 1;
• and y/x satisfies 0.1<y/x <1.5,
• wherein, in the formula, R2, R3 and R4 are independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an aromatic heterocyclic group, an acyl group, an alkoxycarbonyl group or an aryloxycarbonyl group, each of which may have a substituent, two or more of R2, R3 and R4 may be linked together to form a ring, and the ring may have a substituent;
• and A* represents a hydrocarbon-containing group with three or more carbon atoms having an asymmetric carbon atom or axial asymmetry.