Abstract: A compound of formula I optionally in the form of an acid addition salt ##STR1## in which formula: A represents a substituent which is: hydroxyl, O-alkyl, O-cycloalkyl, O-alkenyl, O-aryl, O-aralkyl, O-carbamate, O-carbonate, O-acyl or halogena is 0-5;the substituents A are identical or different when a is more than 1;B represents a C.sub.1 -C.sub.6 aliphatic hydrocarbon group optionally carrying one or more of the substituents: hydroxyl, amino, halogen, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkyl, aryloxy or carboalkoxy and optionally comprising one or more sites of unsaturation and/or one or more carbonyl groups or ketal derivatives thereof;b is 0 or 1;c, d, f and h, which may be identical or different, are 2, 3, 4, 5 or 6; andi is 0 or 1D, E and F, which may be identical or different, represent hydrogen or C.sub.1 -C.sub.