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The secondary enamines derived from 5,6-dihydro-2H-thiopyran-3(4H)-one 1,1-dioxide are in tautomeric equilibrium with their imine forms. With the title electrophiles, either they react at nitrogen or show the usual reactivity at the β-carbon atom of the enamine system. With electrophilic olefins carbocyclization compounds are also formed.

1,2-Oxazine N-oxide derivatives could be obtained as pure isomers from the title reagents. In methanol, they opened into the corresponding Michael-type adducts, as single double bond diastereoisomers. Hydrolyses of both the systems were also highly diastereoselective, leading to ℘-diketones in the former case and to ℘-nitroketones in the latter.

The ionization energy (i.e.) values for electrons in the π MOs of some tertiary amines and enemines derived from morpholine, piperidine and pyrrolidine have been determined by u.v. photoelectron spectroscopy. The effects of structural changes are discussed. The nitrogen lone pair i.e. value is taken as a measure of basicity of amines and enamines in the gas phase. The relative order of basicity is secondary amines < tertiary amines < enamines. This order differs from that found in aqueous solution probably because of solvation effects in the latter.

Hexahydro-pentalene and -indene nitroalcohols are obtained by reaction of 3-(4-morpholinyl)-3-buten-2-one with cyclic nitroolefins. With 1-nitro-cyclohexene a [4 + 2] heterocyclization intermediate Is separated, while an unusual product of double addition is obtained from the hexahydro-pentalene derivative in aqueous acidic medium.

1,2-Oxazine N-oxide condensed heterocycles have been prepared from (E)-1-phenyl-2-nitropropene and enamines derived from 1-methyl-4-piperidone, 4H-tetrahydro-pyran-4-one and 4H- tetrahydro-thiapyran-4-one. They are more stable than the analogous systems derived from cyclohexanone enamines and just like them they are in equilibrium with their open-chain isomers.

Polyfunctionalized aromatic urethanes and heterocyclic compounds are obtained from hydrazinosubstituted enaminoketones.

Die AS-Enamine (I) lassen sich mit β-Nitro-styrol (II) stereospezifisch zu den Produkten (III) umsetzen, deren Hydrolyse die cis-erythro-Ketone (IV) ergibt.

Three linear α-ketoenamines were allowed to react with a series of cyclic and acyclic nitroolefins, to yield aminocyclopentene derivatives with high diastereoselectivity. The corresponding polysubstituted nitrocyclopentanones were obtained by hydrolysis, which also proceeded with a high degree of diastereoselectivity when the system was prochiral.

Trisubstituted 1,4,5,6,-tetrahydro-7H-indolones are obtained in a one-pot synthesis from conjugated nitroolefins and α-ketoenamines derived from α-amino esters and cyclohexane-1,2-dione. In some cases bicyclo[3.2.1]octan-8-one and 1,2-oxazine N-oxide derivatives are isolated.

Phenyl isocyanate attacks both the morpholine and the pyrrolidine enamine derived from 2-tetralone at C-1, whereas β-nitrostyrene attacks the former 80% at C-1 and 20% at C-3 and the latter exclusively at C-3. These results confirm the existence of an equilibrium between the 3,4- and 1,4-dihydro-forms of the enamines.

The ionization energy (i.e.) values for electrons in the π MOs of some tertiary amines and enemines derived from morpholine, piperidine and pyrrolidine have been determined by u.v. photoelectron spectroscopy. The effects of structural changes are discussed. The nitrogen lone pair i.e. value is taken as a measure of basicity of amines and enamines in the gas phase. The relative order of basicity is secondary amines < tertiary amines < enamines. This order differs from that found in aqueous solution probably because of solvation effects in the latter.

The reactivity of the title compounds towards some electrophiles is investigated. An interesting ring-enlargement product is isolated in the reaction of 3-pyrrolidin-1-yl-5,6-dihydro-4H-thiopyran 1,1-dioxide with methanesulphonyl chloride.

The structures and the reactivities of the title vinylogous sulphonamides are compared with those of the corresponding vinylogous amides derived from cyclohexane-1,3-dione. Their behaviour on alkylation, acylation, and addition-substitution has been studied. Isolation of some of the products can be explained in terms of the existence of a tautomeric equilibrium in the parent systems.