C. Russo

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.

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.

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.

Structure and reactivity of enamines derived from 5,6-dihydro-2H-thiapyran-3(4H)-one 1,1-dioxide

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.