Photopolymerizable oxetane derivative and liquid-crystal composition containing it

A compound of a formula (1):

• wherein R1 represents a hydrogen atom or an alkyl group having from 1 to 5 carbon atoms;
• R2 represents a hydrogen atom, —NCO, —NCS, —OCHF2, —CH2F, —OCF2CF2H, —OCF2CHFCF3, or —Y1—(CF2)s-CF3, in which Y1 represents —O—, —S—, —COO—, —OCO—, —CO—, —CH═CH—, or —C≡C—, s indicates an integer of from 0 to 10;
• A1 represents a 1,4-phenylene group, or a 1,4-phenylene group in which any hydrogen atom is substituted with a halogen atom, a cyano group, a methyl group, an ethyl group, a methoxy group, a hydroxy group, a formyl group, an acetoxy group, an acetyl group, a carbonylmethyl group, a carbonyltrifluoromethyl group, a difluoromethyl group, or a trifluoromethyl group;
• A2 and A3 each independently represent a 1,4-cyclohexylene group, a 1,4-phenylene group, a pyridine-2,5-diyl group, a pyridazine-3,6-diyl group, a pyrimidine-2,5-diyl group, a naphthalene-2,6-diyl group, a tetrahydronaphthalene-2,6-diyl group, a 1,4-cyclohexylene group in which any hydrogen atom is substituted with a fluorine atom, or a 1,4-phenylene group in which any hydrogen atom is substituted with a halogen atom, a cyano group, a methyl group, an ethyl group, a methoxy group, a hydroxy group, a formyl group, an acetoxy group, an acetyl group, a carbonylmethyl group, a carbonyltrifluoromethyl group, a difluoromethyl group or a trifluoromethyl group;
• X1 represents a single bond, —O— or —OCO—;
• X2 and X3 each independently represent a single bond, —CH═CH—COO—, —OOC—CH═CH—, —CH2CH2—COO—, —OOC—CH2CH2—, —COO—, —OCO—, —OCH2—, —CH2O—, —OCF2—, —CF2O—, —CH2CH2—, —C≡C—, —NHCO—, or —CONH—;
• m indicates an integer of from 0 to 20;
• and n indicates 1 or 0.