prov:value
| - X1 is a hydrogen atom, a deuterium atom, a halogen atom, or a group selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an alkoxyl group and a sulfide group which are substituted or unsubstituted, an aryl group, a heterocyclic group, and a substituted silyl group, and may be the same or different when b is two or more;
|