gen, hydroxyl, or alkoxy of 1 to 4 carbons; when R2 is hydrogen, X is a divalent radical --Z--R4 --, --R4 -- or --Z--C(???O)--R5 --, and Z is --O-- or --N(R6)--; when R2 is hydroxyl or alkoxy, X is a direct bond or an alkylene diradical of 1 to 4 carbons; R3 is hydrogen, primary alkyl of 1 to 8 carbons, secondary alkyl of 3 to 8 carbons, aralkyl of 7 to 12 carbons or cycloalkyl of 5 to 12 carbons;