Evidence for the Intermediacy of Arylbenzylnitrenium Ions in the Thermal Rearrangement of Isoxazolidines Derived from C,N-Diarylnitrones and 2-Morpholin-4-yl-acrylonitrile
arylbenzylnitrenium ions. Herein, we report that these species can be generated by a process involving an unprecedented thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile. The products from these reactions are dramatically dependent upon the nature of the nitrone. Most of the observed chemistry originates from the singlet state.
One Step Regioselective Synthesis of 5-Aminoisoxazoles from Nitrile Oxides and α-Cyanoenamines
作者:Amar Saad、Michel Vaultier、Aïcha Derdour
DOI:10.3390/90700527
日期:——
The 1,3-dipolar cycloaddition of nitrile oxides to 1-cyanoenamines gives 5-aminoisoxazoles regioselectively. Moderate to good yields could be obtained depending on the method used to generate the nitrile oxides. The intermediate isoxazolines could not be isolated.
The [2+3] cycloadditionreaction between nitrile oxides 2 and the captodative olefins 1 or the methyl crotonate derivatives 4 is regioselective and leads to the formation of the 5-substituted amino-isoxazole 3 or the 4-substituted methoxycarbonyl-isoxazole 5 derivatives, respectively. All these reactions are greatly accelerated by microwave irradiation without changing their regioselectivity with respect
Photoreaction of 2-morpholinoacrylonitrile with substituted 1-acetonaphthones. Part II
作者:Hamid R. Memarian、Masoud Nasr-Esfahani、Dietrich Döpp
DOI:10.1039/b006835g
日期:——
Photochemical reactions of substituted1-acetonaphthones in the presence of 2-morpholinoacrylonitrile were investigated. The type of reaction, photocycloaddition s. photosubstitution, is dependent on the nature of the additional substituent. The location of the additional substituent on the ring also affects the type of addition, [2 + 2] s. [4 + 2].
α-Cyclization of tertiary amines. Part 3. Captodative or push-pull enamines form pyrrolines, pyrrolizidines and their ring homologues with dimethyl acetylenedicarboxylate in a highly diastereoselective reaction
作者:Benoît De Boeck、Shuiping Jiang、Zdenek Janousek、Heinz G. Viehe
DOI:10.1016/s0040-4020(01)85235-2
日期:1994.1
The title one-pot reaction occurs through a sequence of [2+2] cycloaddition, ring opening to dienamines and formation of a 1,5-dipole by [1,6] hydrogen-shift. This intermediate may cyclize or, in sterically suitable cases and at lower temperatures, lead to isolable N-vinyl enamines by proton transfer.