Bernard Laude

Regiochemistry of the cycloadditions of diphenylnitrilimine to coumarin, 3-ethoxycarbonyl and 3-acetyl coumarins: A reinvestigation

Abstract The cycloaddition reactions of diphenylnitrilimine to coumarin, 3-ethoxycarbonyl and 3-acetylcoumarins were studied. The observed regiochemistry of the reaction with the coumarin 4a was the same as the one suggested by other researchers. For the coumarins 4b and 4c bearing an electron withdrawing group at the 3-carbon atom, our results invalidate the previously reported regiochemistry. The presence of an electron-withdrawing group at the 3-C atom of coumarin derivatives reverses the regioselectivity of cycloaddition of diphenylnitrilimine to the dipolarophilic double-bond.

Reaction of diarylnitrilimines with 3-arylidene-4-isothiochromanones. A general approach to the first thiadiazaphenanthrene

Abstract A general synthesis of derivatives of 1,2,4-triphenyl-4,10-dihydro-10-thia-3,4-diazaphenanthrene (a new heterocyclic skeleton) in two steps from 3-arylidene-4-isothiochromanones via cycloaddition route is recorded.

REACTION OF DIPHENYLDIAZOMETHANE WITH N-METHYLOXY- AND N-ETHYLOXYCARBONYL-N-(2,2,2-TRICHLOROETHYLIDENE)AMINES

Reaction of the title imines with diphenyldiazomethane gives a Δ3-1,3,4-triazoline, which leads, after loss of dinitrogen, to a transient azomethine ylide. Subsequent elimination of ethyl or methyl chloroformate gives the unexpected 1,1-diphenyl-4,4-dichloro-2-aza-1,3-butadiene.

Regioselectivity and specificity in cycloaddition of diphenylnitrilimine

Abstract Diphenylnitrilimine cycloaddition reactions on 1,2-dihydronaphtalenes are only regioselective. Use of 1- or 2-tetralones enamines as dipolarophiles allows to attain regiospecificity.

Nucleophilic Additions of Sodium Alkoxides to 4,4‐Dichloro‐1,1‐diphenyl‐2‐azabuta‐1,3‐diene

The reaction of some sodium alkoxides with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene is described. Whereas sodium methoxide, ethoxide or isopropoxide leads to 1,3-bis(alkoxy)- and/or 1,3,4-tris(alkoxy)-2-azabut-2-enes, the sodium salt of ethyl glycolate gives a Δ2-oxazoline. Mechanisms for the formation of these products are proposed.

Reaction of 2-Benzoyl-1,2-Dihydroisoquinaldonitrile Hydrofluoroborate Salt with some 1,4-Quinones

Abstract In all reactions studied up to the present time with olefins, the Reissert hydrofluoroborate salts have given only the Diels-Alder adducts. With 1,4-benzo- and naphtoquinones, we have found evidence for 1,3-dipolar cycloaddition. The structure of cycloadducts was determined from spectroscopic data and specified by a radiocristallographic study.

Utilisation de la spectroscopie RMN 1H à haut champ pour la détermination de la configuration et de la conformation des cycloadduits obtenus par action de diphenylnitrilimine sur divers dihydro-1,2 naphtalenes substitués en 1

Abstract The PMR spectroscopic properties (250 MHz) for cycloadducts of diphenylnitrilimine towards 1,2-dihydronaphthalenes substituted at the C 1 -carbon atom have been studied. The data allow us to determine the stereochemistry of the cycloaddition reaction: the approach of the dipole occurs from the less hindered diastereotopic side of the dipolarophile. The conformation of cyclohexenic moiety of the cycloadducts is an half-boat conformation.

J. nucleophilic additions of the cyanide anion to 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene

The unexpected formation of a 2H-pyrrole by reaction of potassium cyanide with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene and the mechanism of this reaction are described and the structures of the product and a trapped intermediate confirmed by X-ray crystallographic studies.

REACTION OF AN OPEN-CHAIN ANALOGUE OF REISSERT COMPOUND HYDROFLUOROBORATE SALT WITH ETHYL ACRYLATE. A REINVESTIGATION

Abstract The reaction of an open-chain analogue of Reissert compound hydrofluoroborate salt with ethyl acrylate does not give a [4+2] cycloadduct as previously described, but a [3+2] cycloadduct which evolves to a 2-pyridone 15.

Reaction of diarylnitrilimines with 3,3-dimethyl-2-indanone enamines; the first example of a stable zwitterionic nitrilimine–enamine cycloadduct

The reaction of the title compounds leads to a zwitterionic cycloadduct as is demonstrated by 1H, 13C, and 15N n.m.r. spectroscopy