oup, t is an integer of 1 to 6 which indicates the number of (CR<1>R<2>OH) group or (CR<1>R<2>CO2R<3>) group, s is an integer of 0 to 5 which indicates the number of (CHR<1>R<2>) group, and n is an integer of 0 to 5 which indicates the number of X, where t + s + n = 6. 7.