What is described are compounds ##STR00001## wherein R represents Br, I or R.sup.1--SO.sub.3, where R.sup.1 is an unsubstituted or substituted C.sub.1 C.sub.5-alkyl group, or an unsubstituted or substituted phenyl group; X is O or NR'', where R'' is a usual protective group for N; and R' represents hydrogen, a halogen, such as F, Cl, and Br, a substituted or unsubstituted C.sub.1 C.sub.7-alkyl group, such as methyl and ethyl, a substituted or unsubstituted C.sub.2 C.sub.7-alkenyl group, or a substituted or unsubstituted C.sub.2 C.sub.7-alkynyl group.