The formulae described in this abstract are to be found on the fold-out flow sheets. Abbreviation E≡COOCH₃. The Introduction surveys the results obtained since a 1962 review from investigations of the reactions of heterocyclic compounds and acetylenic esters. The chemistry of the cycl[3,2,2] azine system [1] first described in 1958 is discussed and particular mention is made of the syntheses of derivatives of compound [1] from indolizine [2] and acetylenic esters. Chapter One describes the investigation of the reactions of the potentially dienic systems [3]-[6] with tetracyanoethylene and hexachlorocyclopentadiene. The indolizine [3] did not react with either dienophile and this failure is attributed to the steric and electron-withdrawing effects of the 3-ester group. The 4H-quinolizine [4] gave complex mixtures of products with both dienophiles on the evidence of thin-layer chromatography. Parallel treatment of the reaction mixtures from the 9aH-quinolizine [5j and tetracyanoethylene, and from the dihydroindole [6] and hexachlorocyclopentadiene, suggested similar results, whilst compounds [5] and [6] were recovered when the corresponding dienophiles were interchanged.