| abstract |
Compounds of the structure wherein R and R' are H, alkyl or aryl and each Z, X, Y and X' is H, acylamino, acyloxy, alkanoyl, alkoxycarbonyl, amino, alkyl, alkoxy, hydroxy, alkylamino, dialkylamino, arylamino, alkylaryl, diarylamino, halo, carboxyl or cyano; and Z can also be effective UV blockers. |