Mustapha Kaafarani

SYNTHESE ET REACTIONS SRN1 EN SERIE 5-NITROTHIAZOLE

A new heterocyclic reductive alkylating agent, the 2-methyl-4-chloromethyl-5-nitrothiazole, has been synthesized and could react with the 2-nitropropane anion as nucleophile, to give the 2-methyl-4-(2-methylpropenyl)-5-nitrothiazole as the major product. The reaction was shown to proceed by the SRN1 mechanism which was confirmed by the classical criteria for SRN1 reaction: the leaving group effect, the electronwithdrawing group effect and classical inhibition experiments by dioxygen, p-dinitrobenzene, cupric chloride or di-tert-butylnitroxide. This reaction has been extended to nitrocyclopentane and nitrocyclohexane anions with lower yields.

Fast electron transfer C-alkylation of 2-nitropropane anion under microwave irradiation

Microwave irradiation is shown to be an attractive methodology for fast electron transfer C-alkylation reactions of 2-nitropropane anion by different reductive alkylating agents. This method is simple, rapid and affords excellent C-alkylation yields.

Synthesis of Cαα-unsymmetrically disubstituted nitroesters by electron transfer C-alkylation of ethyl 2-nitropropionate anion

Abstract The ethyl 2-nitropropionate anion was shown to react with six reductive alkylating agents to give new C αα -unsymmetrically disubstituted nitroesters and in some cases new ethyl monosubstituted methacrylates. The C -alkylation was shown to proceed by the S RN 1 mechanism which was confirmed by the classical criteria for S RN 1 reaction: the electron-withdrawing group effect and classical inhibition experiments by dioxygen, p -dinitrobenzene, cupric chloride or TEMPO. For example, ethyl 2-methyl-2-nitro-3- p -nitrophenylpropionate was transformed in the corresponding amino acid.

A new synthetic approach for novel 4-substituted-5-nitroimidazoles

Abstract A new synthetic approach, involving an SRN1 reaction of the anion of 1-methyl-4-phenylsulfonyl-methyl-5-nitro-1H-imidazole with 2,2-dinitropropane and a radical anion or a concerted radical reductive elimination of sulfonyl and nitro groups affords an original 5-nitroimidazole bearing a trisubstituted ethylenic double bond at 4-position.

Synthese de thia-7 aza-1 bicyclo (4,3,0) nonanes par reaction radiocalaire regioselective.

Abstract Several β-aminothiols prepared from 3-piperideine and different thiiranes react by free radical reactio chemically initiated to yield exclusively 7-thia-1-azabicyclo (4,3,0) nonane derivatives. Even when this process is in competition with a radical addition on a terminal ethylenic chain, the bicyclic thiazolidine is always the major product.

First, serendipitous and intriguing hydrolysis of a tertiary nitroalkane

Abstract The hydrolysis of 1,2-dimethyl-4-(1,1,2-trimethyl-2-nitropropyl)imidazole which leads to two tertiary alcohols formed respectively by CNO2 and CC bond fission, is the first example of hydrolysis of a tertiary nitroalkane. It might be explained by an intramolecular nucleophilic catalysis favored by a double gem-dimethyl effect and a possible anchimeric assistance by imidazole group.

Synthesis of a new imidazo[4,5-b]pyridin-5-one via a vicarious nucleophilic substitution of hydrogen

A new imidazo[4,5-b]pyridin-5-one was prepared in five steps from 4(5)-nitro-1H-imidazole via a vicarious nucleophilic substitution of hydrogen of 1-benzyl-4-nitro-1H-imidazole with the carbanion generated from chloroformand potassium tert-butoxide. Hydrolysis of 1-benzyl-5-dichloromethyl-4-nitro-1H-imidazole and Knoevenagel condensation between the resulting aldehyde and diethyl malonate catalyzed by titanium(1V) chloride gave the corresponding 4-nitroimidazole bearing at 4 position the diethyl methylenemalonate group. Reduction and cyclization afforded the required ethyl 1-benzyl-5-oxo-4,5-dihydro-1H-imidazo[4,5-b]pyridine-6-carboxylate.

A Convenient Synthesis Of 4-Substituted-5-nitroimidazole Building Blocks

Abstract The nitration of 1,2-dimethylimidazoles bearing at the C4 position a chain with a tertiary alcohol or a terminal alkene gives rise to 5-nitroimidazoles in which the side chains are converted in β-nitroalcohols. These compounds treated with base to splitt off nitromethane anion afford ketones. This represents a preparatively useful and convenient route to new 4-substituted 5-nitroimidazoles.

SYNTHESIS OF 7-THIA-1-AZABICYCLO (4,3,0) NONANE DERIVATIVES VIA FREE RADICAL REACTION

Abstract Several β-aminothiols were prepared by condensation of 3-piperideine and different thiiranes.