A. Risaliti

Vinylamines—VIII : The reaction of cyclohexanone enamines with 1- and 2-nitropropene

Abstract Enamines containing a trisubstituted double bond were obtained by reaction of morpholine, piperidine and pyrrolidine enamines of cyclohexanone with 1-nitropropene. Different results were obtained in the reaction of the same enamines with 2-nitropropene. A cycloaddition reaction occurred between 1-N-morpholino-cyclohexene and 2-nitropropene in ether at 0°, leading to an oxazine derivative. The structures of the products were determined by spectral and chemical evidence. In acetonitrile at 0° or in ether at room temperature the same enamine reacted with 2-nitropropene to give an enaminic mixture, where the less substituted alkylated isomer appeared to be the minor component. Analogous behaviour was shown by piperidine and pyrrolidene enamines. The mechanism and the stereochemistry of these reactions have been discussed. The formation of diadducts of a different nature from morpholine and pyrrolidine enamines with excess 2-nitropropene is also reported.

Vinylamines—XIV : Nitroalkylation of enaminic equilibrium mixtures

Abstract A rapid equilibrium is present in enaminic systems derived from 3-substituted cyclohexanones. Their reactions with β-nitrostyrene have been studied and the stereochemical implications discussed.

Bicyclic 1,2-oxazine N-oxides. Different behaviour in ring fission between systems derived from 5- and 6-membered ring cyclic enamines

Abstract 1,2-Oxazine N-oxides derived from aminocyclohexenes open into the corresponding nitroalkylated trisubstituted enamines, whereas those derived from aminocyclopentenes give stable tetrasubstituted enamines. Both open-chain systems are easily hydrolyzed to the corresponding γ-nitrocycloalkanones.

Octaline and decalone derivatives from a new annulation reaction in enamine field

Abstract An octaline system is obtained from the reaction between 2-cyclohexenyl-1-morpholino-ethene and β-nitrostyrene, carried out under kinetic control. By hydrolysis, it is converted to a 1-decalone derivative, which is also a kinetic control product. The stereochemical aspects of formation and equilibration of the products are examined.

Vinylamines—XV : Unusual stereochemical course in nitroalkylation of biased enaminic systems

Reactions between 1-nitropropene and 3-phenyl-, 3-t-butyl- and 4-t-butyl-cyclohexanone enamines are described. Both parallel and antiparallel attacks of the olefin on the substrates are possible.

Vinylamines—VII: More substituted alkylated enamines from cyclohexanone enamines and phenyl vinyl sulfone

Abstract The morpholine and piperidine enamines of cyclohexanone reacted with phenyl vinyl sulfone to give mainly the more substituted alkylated enamines. The structure of the products was determined by spectral and/or chemical evidence. Different results were found for the pyrrolidine enamine. The possible mechanism and the factors affecting the stereochemistry of the reactions are discussed.

Cyclization of γ,δ-epoxy-α-cyanosulphones. A simple, diastereoselective route to cyclopropane carboxylic acids.

Abstract cyclisation of α-cyano-α-sulphonyl-γ,δ-epoxy carbanions proceeds with high yields and complete diastereoselectivity, to yield cyclopropanolactones, useful intermediates in the synthesis of cis -substituted cyclopropane carboxylic acids.

1,3,4-Oxadiazine derivatives from cyclohexanone enamines and asymmetric diimides : Possibility of ring-chain tautomerism in such heterocyclic system

Abstract 1,3,4-oxadiazine derivatives, in equilibrium with their corresponding trisubstituted enamine isomers, are obtained in a regiospecific way from cyclohexanone enamines and ethoxycarbonyl aroyl diimides. Such an equilibrium is not present in analogous oxadiazine systems, derived from aryl aroyl diimides.

α-Nitrostyrene. First reactions with enamines

Abstract The reactivity of the title nitroolefin towards conformationally locked enamines is examined. A comparison with its isomer β-nitrostyrene is also made.

Reactions of conjugated arylazocycloalkenes with grignard reagents—43: Parallel and antiparallel attacks of grignard hydrocarbon moiety on some arylazocycloalkenes

Abstract Conjugated phenylazocycloalkenes sterically hindered towards the antiparallel attach react with PhMgBr via parallel attack, to givesyn-phenylhydrazones. When such a sterical hindrance is absent in the azoalkenes, the reaction occurs via antiparallel attack even when the arylmagnesium bromide bears a particularly hindering aryl group. The conformation of thesyn-phenylhydrazones obtained by the above reactions and those of the corresponding ketones are discussed with the aid of the benzylic proton NMR analysis.