Patent ID: 7456311

Claim:
An adamantane derivative having a structure represented by formula (I-a): wherein: R 1 represents a hydrogen atom, a methyl group, or a trifluoromethyl group; R 2a represents a C1 to C30 alkyl group or a hydrocarbon group containing a C3 to C30 cycloalkyl group or a C6 to C30 aryl group, the alkyl group or the hydrocarbon group having a sulfide group; each of X 1 and X 2 represents an oxygen atom or a sulfur atom; Y represents a C1 to C10 alkyl group, a halogen atom, a hydroxyl group, or a mercapto group, or two Ys are linked to form ═O or ═S; a plurality of Ys may be identical to or different from one another; k represents an integer of 0 to 14; and each of m and n is an integer of 0 to 2.