Examples of the substituent for the alkyl group include halogen atoms, alkoxy groups such as methoxy, ethoxy, methoxyethoxy and phenoxy; sulfide groups such as methylthio, ethylthio and propylthio; alkylamino groups such as methylamino and propylamino; acyl groups such as acetyl, propanoyl, octanoyl and benzoyl; acyloxy groups such as acetoxy, pivaloyloxy and benzoyloxy; aryl groups, heterocyclic