and particularly preferably having 7 carbon atoms, such as phenoxycarbonyl), a heterocyclic oxycarbonyl group (preferably having from 2 to 20 carbon atoms, more preferably having from 2 to 12 carbon atoms, and particularly preferably having from 5 to 6 carbon atoms, such as thienyloxycarbonyl and pyridyloxycarbonyl), an acyloxy group (preferably having from 2 to 20 carbon atoms, more preferably fr