M. Forchiassin

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—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.

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.

Vinylamines—X : Selectivity and stereochemistry of the reactions of 2-methylcyclohexanone enamines with ethyl azodicarboxylate and phenyl isocyanate☆

Abstract Morpholine, piperidine and pyrrolidine enamines of 2-methylcyclohexanone react with ethyl azodicarboxylate to give, after hydrolysis, 2-methyl-6-(N,N′-dicarbethoxy)hydrazinocyclohexanone in 49%, 47% and 84%, yield, respectively. The same enamines by reaction with phenyl isocyanate and subsequent hydrolysis furnish 2-methyl-6-phenylcarbamylcyclohexanone in 51%, 42% and 88% yield, respectively. These results reflect the percentages of the less substituted isomeric enamines and are in good agreement with those determined by NMR spectroscopy, 1-N-Morpholino-, 1-N-piperidino- and 1-N-pyrrolidino-2-(N,N′-dicarbethoxy)hydrazinocyclohex-1-en by kinetically controlled acidic hydrolysis, lead to the 2,6-disubstituted cyclohexanone having trans configuration, as results from NMR analysis and equilibration into the more stable cis isomer. The stereochemistry of such a reaction is reported and discussed.

Reactions of cyclohexanone enamines with asymmeric diimides

Abstract Tetrasubstituted enamine derivatives which rearrange into 1,3,4-oxadiazine isomers have been isolated from aryl acyl diimides and 1-morpholinocyclohexenes. The same reactions with 1-pyrrolidinocyclohexenes have led directly to the cyclic derivatives.

Reactions of enamines from trans-decalin-2-ones with β-nitrostyrene and phenyl vinyl ketone, and X-ray analysis of 2-p-bromophenyl-4a,5,5a,6,7,8,9,9a,10,10a-decahydro-5a-methyl-10a-morpholino-4H-naphtho[2,3-b]pyran

Only the Δ2-isomers of the morpholine enamines from trans-decalin-2-one (1) and 4a-methyl-trans-decalin-2-one (9) react with β-nitrostyrene and phenyl vinyl ketone to give the enaminic adducts (2) and (13), and the naphthopyran derivatives (5) and (16a), respectively. The structures of the products (2), (5), and (13) were assigned from spectral data and their hydrolysis products, while that of (16a) was made through X-ray analysis. The enamine (9) displays reduced reactivity with respect to enamine (1) in the foregoing reactions.

Cyclohexanespirocompounds from 1-aminocyclohexenes and phenylcarbamoyldiimide

Abstract The unexpected behaviour of phenylcarbamoyldiimide towards 1-amino-cyclohexenes, leading to enamine derivatives bearing a cyclohexanepirotriazolidinone substituent is reported.

Reactivity of p-bromophenyl vinyl sulphone towards the morpholine enamine from 4a-methyl-trans-decalin-2-one. Crystal and molecular structure of 1α-(2-p-bromophenylsulphonylethyl)-4a-methyl-2-morpholino-Δ2-trans-octalin

The morpholine enamine from 4a-methyl-trans-decalin-2-one reacts with p-bromophenyl vinyl sulphone when heated under reflux in dioxan to give a mixture of 1α- and 3-(2-p-bromophenylsulphonylethyl)-2-morpholino-Δ2-trans-octalin [(6) and (3) respectively]. The structure of (6) was determined by X-ray analysis, while that of (3) was assigned on the basis of spectroscopic properties and chemical behaviour. A possible pathway for the formation of the two enamine derivatives is discussed. The crystal structure was determined by the heavy-atom method from diffractometer data and refined by least squares to R 0.094 for 2 260 independent reflections.