. . . "in which n is an integer from 1-5 and Z is divalent hydrocarbyl radical including alkyl, alkenyl, cycloalkyl, aryl and aralkyl of up to about 10 carbon atoms; A is H or OR; and R is H or a blocking group, e.g. trityl, methoxytrityl, dimethoxytrityl, dialkylphosphite, pivalylisobutyloxycarbonyl, t-butyldimethylsilyl, and similar such blocking groups," .