Catalytic hydrogenation over platinum metals By . Academic Press Inc., New York and London, 1967. xii + 550 pp. Price $dollar;22.50

We report a novel intramolecular 1,6 oxa-Michael addition on substituted dihydropyridines to obtain 5 and 6 member ring lactones in an one-pot reaction starting from activated pyridinyl propenones, without organic catalysis or presence of bulky groups in the Michael acceptor. A marked dependence on the regioselectivity of ring closure was found, dependent on the propenone used.