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The alkyl-substituted heterocyclic carbonitriles 1–3 react with elemental sulphur to yield the thienoazines 7, 11 and 13, respectively. Whereas 7 reacts with acrylonitrile to afford a [4+2] cycloaddition product with elimination of hydrogen sulphide, compounds 11 and 13 are not converted into cycloadducts. The quinoline 9a and the quinazoline 14 are obtained by reaction of 1 and 3, respectively, with formaldehyde and malononitrile. The thienopyridines 16 are produced by reaction of 6a, c with benzylidinemalonitrile. Furo[3,4-f]indazole 19 is prepared by [4 + 2] cycloaddition of the thienopyrazole 18 with maleic anhydride. The effect of the substituent of the thienyl moiety of the thienopyridazine ring system on its reactivity toward electron-poor olefins has been investigated.

Ethyl (5-cyanomethyl-1,3,4-oxadiazol-2-yl)acetate (4) could be prepared by condensing cyanoacetohydrazide (2) with diethyl monoimidic malonate (1). The reactivity of 4 towards a variety of electrophilic reagents is reported. The reaction of 1 with 2-amino-1-propene-1,1,3-tricarbonitrile gives the pyridine 12 which is converted into pyridopyridazine 13 on coupling with benzenediazonium chloride.