Yu. P. Dormidontov

Organodimagnesium derivatives of thiophene. 3. Synthesis of an organodimagnesium derivative of hexabromo-2,2′-dithienyl and its reaction with oxalic acid esters

It was established that the reaction of hexabromo-2,2′-dithienyl with magnesium in the presence of ethyl bromide gives an organodimagnesium derivative, which reacts with oxalic acid esters to give 3,3′,4,4′-tetrabromo-5,5′-dithienyl-diglyoxalic acid esters. Reduction of the latter with ethylmagnesium bromide leads to 3,3′,4,4′-tetrabromo-5,5′-dithienyl-2,2′-diglycolic acid esters.

Reactions of halogen metal alkoxides

The study of the thermal stability of halogen-magnesium alkoxy-carbinolates was continued. The data obtained led to the development of procedures for the synthesis of esters of α-oxo and of α-hydroxy-acids containing the thienyl radical. An intramolecular hydrogen bond between the sulfur atom and the hydrogen of the hydroxyl group in esters of (5-bromothienyl-2)glycolic acid was revealed. The presence of this bond was confirmed by infrared spectroscopic data and by the results of the investigation of the esters of (thienyl-3)- and (4-bromothienyl-3)glycolic acids.

Reactions of metal halide-alkoxides

A method has been developed for the synthesis of esters of thiophene-2,5-diglyoxylic acid from iodomagnesium derivatives of thiophene-2,5-dicarbinols. The formation of products of the second stage of the reaction-2,2′-di(alkoxalyl)-5,5′-oxalyldithiophenes-has also been established. The IR spectra of the compounds obtained have been studied.

Reactions of halogenometalalkoxides

Investigation of the thermal stability of halogenometalalkoxides obtained by reacting Grignard compounds with esters of oxalic acid and containing an indolyl group, is continued. Despite the aromatic nature of the indolyl radical, the ordinary decomposition of the halogenomagnesiumalkoxides with splitting off of aldehyde (ketone) does not take place at 40‡–110‡ C. This is due to hydrogen bonding between hydrogen on the nitrogen and the alkoxy group. The IR spectra of the esters of N-indolyl- and α-indolylglyoxylic acids synthesized are investigated. The latter are shown to contain a hydrogen bond between the NH group hydrogen and the carbonyl group.

Nitrogenous heterocycles. 6. Reactions of organomagnesium derivatives of 7-aza- and benzoindoles with diethyl oxalate and the reactivity of ethoxalylindoles

The reactions of organomagnesium derivatives of 2-methyl- or 2,3-dimethyl-7-azaindoles and 2,3-dimethylbenz[4,5]- or -[6,7]indoles with diethyl oxalate, and the reactivity of the resulting ethoxalylindoles towards phenylmagnesium bromide, have been examined. It has been shown that the course of the reaction is dependent on the solvent and the structures of the starting materials.

Organodimagnesium derivatives of thiophene: 4. Reaction of organodimagnesium derivatives of thiophenes that contain aryl substituents in the ring ? position with diethyl oxalate

It was established that 2,5-dibromo-3-R-4-arylthiophenes form organodimagnesium compounds in ether with the “accompaniment” of dibromoethane. It is shown that because of steric hindrance, only 2-ethoxalyl-3-R-4-arylthiophenes are formed in the reaction of the organodimagnesium compounds with diethyl oxalate. It was established that the bromomagnesiumethoxycarbinolates obtained from the indicated thiophenes and bromomagnesium ethoxide have high thermal stabilities. The IR and PMR Spectra of the synthesized compounds were studied.

Reduction of halogenated ketones with magnesium haloalkoxides

The degree of thermal stability of magnesium haloalkoxycarbinolates containing thienyl groups and dichloro-, trichloro-, and trifluoromethyl groups was explained. The effect of substituents in the thienyl group on the stability of the magnesium haloalkoxycarbinolates was studied.