Pyridazine, pyrimidine and pyrazine ethyne compounds

In accordance with the present invention, there is provided a novel class of heterocyclic compounds. Compounds of the invention contain a substituted or unsubstituted six membered heterocyclic ring that includes at least two nitrogen atoms. The ring additionally includes four carbon atoms. The heterocyclic ring has at least one substituent located at a ring position adjacent to a ring nitrogen atom. This mandatory substituent of the ring includes a moiety (B), linked to the heterocyclic ring via a carbon-carbon triple bond. The mandatory substituent is positioned adjacent to the ring nitrogen atom. Invention compounds are capable of a wide variety of uses. For example heterocyclic compounds can act to modulate physiological processes by functioning as agonists and antagonists of receptors in the nervous system. Invention compounds may also act as insecticides, and as fungicides. Pharmaceutical compositions containing invention compounds also have wide utility.