T. T. Vasil'eva

Radical cyclization of allyl α-bromocarboxylates into λ-butyrolactones. Effect of the ester structure on the cyclization

Allyl dibromoacetate, allyl α-bromopropionate, and allyl phenylbromoacetate undergo cyclization in benzene in the presence of increased concentration of Fe(CO)5—DMF as the initiating system to give the corresponding bromo-substituted butyrolactones.

Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)5

Reformatsky-type addition of esters of α-halogeno carboxylic acids to aldehydes and ketones in the presence of Fe(CO)5 and an activating agent (CBrCl3 or I2) afforded the corresponding esters of β-hydroxy acids in good yields. Possible reaction mechanisms are discussed.

Homolytic addition of bromine-containing addends to cyclohexene

The addition of XBr (X=CCl3, CHBr2, CH2CO2Me, or PhCH2) to cyclohexene in the presence of benzoyl peroxide (BP) or Fe(CO)5+DMF was studied. In the presence of BP, a product of the addition of the Br and PhCO2 radicals is formed along with the expected adduct. The content of the former increases as the efficiency of XBr as the carrier of the chain reaction decreases.

Intramolecular cyclization of chloral allyl hemiacetal under the action of the Fe(CO)5-DMF system

Chloral allyl hemiacetal undergoes cyclization in the presence of the Fe(CO)5-DMF system to form 3,3,5-trichloro-2-hydroxytetrahydropyran rather than a butyrolactone derivative.

Homolytic addition of benzylidene bromide to trimethylvinylsilane and 1-hexene

Benzylidene bromide reacts with unsaturated compounds CH2=CHR (R = Bu, SiMe3) in the presence of benzoyl peroxide to give PhCHBrCH2CHRBr adducts.

Study of the mechanism of the addition of benzyl bromide to trimethylvinylsilane in the presence of the Fe(CO)5—DMF system

The general kinetics of the addition of benzyl bromide to trimethylvinylsilane in the presence of the Fe(CO)5—DMF system has been studied. The reaction orders with respect to each reagent found in the study correspond to a radical chain mechanism of the process. The metal-complex system takes part only in the initiation stage and only at a strictly defined ratio of the components.

Radical-type addition of benzyl bromide to vinyl chloride: the kinetics and activation energy of the process

Radical telomerization of vinyl chloride with benzyl bromide and the competitive reaction of benzyl bromide with vinyl chloride and trimethylvinylsilane have been studied. The relative rate constant for the addition of C6H5C · H2 to vinyl chloride,krel (with respect to trimethylvinylsilane), is close to unity, whereas the activation energy of the addition of C6H5C.H2 to vinyl chloride is considerably lower (by 7 kcal mol−1) than in the reaction involving trimethylvinylsilane. The possible fragmentation of the radical-adduct C6H5CH2CH2C.HCl was suggested as one of the possible reasons of underestimation ofkrel. The activation energy was estimated by the MPDO/3 method.

Relative kinetics of the radical addition of benzyl bromide to unsaturated compounds

The relative rate constants of the addition of the C6H5CH2 radical to unsaturated compounds CH2=CHX (X = C4H9, SiMe3, CF3, CO2Me, CN) were determined under the conditions of initiation by the Fe(CO)5 + DMF system or by benzoyl peroxide. Depending on the values of the relative addition rate constants, the monomers can be arranged into the following series (X): CF3≈C4H9<SiMe3<CO2Me<CN. The relatively nucleophilic character of the benzyl radical has been shown. It was found that under the initiation conditions by the Fe(CO)5 + DMF system, the addition stage proceeds by a free radical mechanism.

Homolytic addition of benzyl bromide to unsaturated compounds in conditions of metal-complex initiation

Radical addition of benzyl bromide to unsaturated compounds containing substituents of a different polar nature, CH2=CHX (X=C4H9, SiMe3, CF3, CO2Me, CN, H), was conducted in the presence of the Fe(CO)5 + DMF (HMPA) system. Adducts were obtained and their structure was demonstrated by13C NMR and mass spectrometry.