New thiophene compounds as intermediates

Amides of the formula V:

• ##STR117## in which X, n, a, b, c, R.sub.1, R.sub.2, R and R' are as defined as follows:
• X is selected from the group consisting of:
• a hydrogen atom, halogen atoms, straight-chain and branched alkyl and alkoxy radicals each having from 1 to 5 carbon atoms, and dialkylamino radicals in which each alkyl group has from 1 to 5 carbon atoms;
• n is selected from the group consisting of:
• 1 and 2;
• a is selected from the group consisting of:
• integers of from 2 to 6 inclusive;
• b is selected from the group consisting of:
• 2 and 3;
• c is selected from the group consisting of:
• 1 and 2, and is such that b+c=4;
• R.sub.1 and R.sub.2, which may be the same or different, are each selected from the group consisting of:
• a hydrogen atom and alkyl radicals having from 1 to 5 carbon atoms, and
• R.sub.1 and R.sub.2 together with the carbon atom to which they are bonded form a hydrocarbon ring having from 3 to 6 carbon atoms inclusive;
• and
• R and R', which may be the same or different, are each selected from the group consisting of:
• a hydrogen atom and alkyl radicals having from 1 to 5 carbon atoms, and
• R and R' together with the nitrogen atom to which the are bonded form a heterocyclic radical selected from the group consisting of -5- and 6-membered heterocyclic radicals each having in addition to carbon atoms only one nitrogen atom, one nitrogen atom and one oxygen atom, or two nitrogen atoms, and each of these heterocyclic radicals substituted by a substituant selected from the group consisting of:
• straight-chain and branched alkyl radicals having from 1 to 5 carbon atoms inclusive and arylalkyl, haloarylkyl, (C.sub.1 -C.sub.5)alkyl-arylalkyl and (C.sub.1 -C.sub.5)alkoxy-arylakyl radicals, in which the alkyl moiety of each aryl-alkyl radical has from 1 to 5 carbon atoms inclusive.