| abstract |
Disclosed are novel first to fourth lactone compounds. The first lactone compound is represented by the formula (1) below. (1) In the formula, X represents CH2, CH2CH2, O, S or NR1; R1 represents a hydrogen atom or a straight chain, branched or cyclic alkyl group having 1-10 carbon atoms. A part or all of hydrogen atoms in the alkyl group may be substituted by fluorine atoms, and a part of the alkyl group may include an atomic group containing an oxygen atom, a sulfur atom, a nitrogen atom, a carbon-carbon double bond, a carbonyl group, a hydroxy group or a carboxyl group. |