2-(l-Ethoxycarbnyl-4-oxoalkyl)-2-imidazolines add organometallic carbon nucleophiles to produce new lactones, whereas hydrogenation affords 1,4,5,6tetrahydropyridines and piperidines via a novel reductive cyclisation-cleavage pathway. We have recently reported (Scheme 1) the synthesis of 2-(4-oxoalkyl)-2-imidazolines (2) and (3) by the conjugate (1,4) addition to a&unsaturated ketones of the enaminocster (l),' acting as an equivalent to the 2imidazoline (4,5-dihydroimidazole) nucleophile (4).2 Our motivation for exploring the conjugate additions had been to access potential acetylcholine agonists at muscarinic receptors (muscarine;5); with the atnidine function (protonated at physiological pH) mimicing the quaternary nitrogen, we envisaged the imidazoline unit linked through C-2 to an oxygen heterocycle as a target framework. 1 The reaction of nucleophiles with the ketone function of adducts (2) with subsequent lactonisation looked suited to generate such a system. We report here the reaction of nucleophiles with the adducts (2). Carbon nucleophiles indeed form new lactones of potential biological interest, but with hydride nucleophiles and other reductive conditions the reaction takes a completely different course and provides a novel synthesis of tenahydropyridines and piperidines.