Hydroxymethylpolythiophene derivatives

A compound of the formula:

• ##STR18## in which n is 0;
• R is --CH(R.sup.1)OCH.sub.3, --CH(R.sup.1).OR.sup.2, CH(R.sup.1).O(C.sub.2 -C.sub.6 alkyl), --CH(O--Z).sub.2, or --COR.sup.3 ;
• R.sup.1 is H, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.1-6 alkoxy, or C.sub.1-6 acyloxy;
• each R.sup.2 and R.sup.4, independently, is H, C.sub.2-6 alkenyl, C.sub.1-6 hydroxyalkyl, C.sub.2-6 alkoxyalkyl, tetrahydropyranyl, or --CO--Y--COOH;
• and
• R.sup.3 is H, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, or C.sub.1-6 alkoxy;
• wherein Z is C.sub.1-6 alkyl, C.sub.2-6 alkenyl, or C.sub.1-6 acyl;
• and Y is C.sub.1-6 alkylidene, C.sub.2-6 alkenylidene, or phenylene provided that R and --CH(R.sup.1).OR.sup.4 cannot both be CH2OH and further provided that when R is CHO, --CH(R.sup.1).OR.sup.4 cannot be CH2OH;
• or a salt or an ester thereof.