Imidazolium cations and processes for their preparation

A process for the preparation of a compound of the formula ##STR20## wherein A is a heteroaromatic ring, which may be optionally substituted by one or more R.sup.1 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, cyano or carboxy substituents;

• wherein P or Q are optional substituents, each independently a substituent selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, cyano or carboxy, or P and Q together are a heteroaromatic ring, said P and Q substituents independently or together which may optionally be substituted by one or more R.sup.3 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, or carboxy substituents;
• C is an optional substituent which is an aromatic or heteroaromatic ring, which may optionally be substituted by one or more R.sup.2 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, or carboxy substituents;
• R.sup.4 is hydrogen, a lower alkyl or aryl group, or together with R.sup.5 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one alkyl group;
• R.sup.5 is a lower alkyl or aryl group, or together with R.sup.4 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one lower alkyl group;
• and X is an anion, which comprises reaction of a compound of the formula II ##STR21## wherein A, C, P, Q, R.sup.1, R.sup.2 and R.sup.3 are as hereinbefore defined, with an N-substituted or N,N-disubstituted formamide of the formula III ##STR22## wherein R.sup.4 and R.sup.5 are as hereinbefore defined, in stoichiometric amounts, in the presence of a first halogenating agent;
• and wherein said compound (II) has at least one additional N--C--C--N moiety which is reacted in a second step with a reactant selected from the group consisting of an N-substituted formamide, an N-substituted or N,N-disubstituted thioformamide, an N-substituted or N,N-disubstituted formamide acetal, and an N-substituted or N,N-disubstituted thioformamide acetal, in the presence of a second halogenating agent.

A compound of the formula ##STR23## wherein A is a heteroaromatic ring, which may be optionally substituted by one or more R.sup.1 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, cyano or carboxy substituents;

• P or Q are optional substituents, each independently a substituent selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, or carboxy, or P and Q together are a heteroaromatic ring, said P and Q substituents independently or together which may optionally be substituted by one or more R.sup.3 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, cyano or carboxy substituents;
• C is an optional substituent which is an aromatic or heteroaromatic ring, which may optionally be substituted by one or more R.sup.2 substituents selected from the group consisting of aryl, heteroaryl, alkyl, hydroxy, halo, lower alkylamino, amino, nitro, cyano or carboxy substituents;
• R.sup.4 is hydrogen, a lower alkyl or aryl group, or together with R.sub.5 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one lower alkyl group;
• R.sup.5 is a lower alkyl or aryl group, or together with R.sup.4 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one lower alkyl group;
• and X is an anion, and wherein at least one of said A, C, P or Q, R.sup.1, R.sup.2, or R.sup.3 substitutents comprises an imidazolium group substituted with a group of the formula --N(R.sup.6)(R.sup.7), wherein R.sup.6 is hydrogen, a lower alkyl or aryl group, or together with R.sup.7 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one lower alkyl group;
• R.sup.7 is a lower alkyl or aryl group, or together with R.sup.6 and the nitrogen atom to which it is attached, form a heterocyclic ring having from 5 to 7 members, which may optionally contain a sulfur, oxygen, silicon, selenium or an additional nitrogen atom, said ring optionally substituted with at least one lower alkyl group, with the proviso that the combination of R.sup.6 and R.sup.7 is different from the combination of R.sup.4 and R.sup.5.