A. B. Terent'ev

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.

A spin-trap ESR study of the regrouping of radicals with 1,3 or 1,5 hydrogen migration

Spin-trap (2-methyl-2-nitrosopropane) ESR methods have been used to demonstrate the formation of R1O2CĊR2CH2CH2C6H13 (R1=H, CH3 and R2=Cl, CH3) radicals during the photoinitiated reaction (λ ∼ 2537 A) of 1-octene with BrCHClCOOH and CH3CHBrCOOCH3 in the presence of tert-outyl peroxide and (C3H5)3SiH. Formation of these radicals indicates regrouping of the R1O2CCHR2CH2ĊHC6H13 radical with 1,3 H atom migraion and, possibly, regrouping of the R1O2CCHR2CH2CH(C6H13)CH2CHC6H13 radical with 1,5 H atom migration.

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.

Charge transfer complexes as possible intermediates in free radical addition and telomerization reactions initiated by metal carbonyl systems

Spectral data were obtained for the charge transfer complexes formed by CBr4 with Mn2(CO)10, Fe(CO)5, and M(CO)6 (M=Cr, Mo, and W) in the Fe(CO)5 -DMF system. A qualitative correlation was found between the position and intensity of the charge transfer band and the efficiency of these systems as initiators of homolytic addition and telomerization reactions, proceeding with dissociation of a C- Br bond in the telogen.

RADIATION-CHEMICAL TELOMERIZATION OF ETHYLENE WITH METHYL FORMATE.

1. The radiochemical telomerization of ethylene with methyl formate has been studied over the temperature range 125–190°. 2. A rearrangement of radicals with 1,6-migration of hydrogen atoms took place during the course of the reaction.

Rearrangement of radicals in the telomerization of ethylene with methyl formate

1. In the telomerization of ethylene by methyl formate in the presence of peroxide, together with the methyl esters of acids of normal structure, the methyl ester of α-ethyloenanthic acid and the propyl ester of propionic acid are produced. 2. A mechanism was proposed for the formation of these esters, including the rearrangement of radicals with 1,6- and 1,5-migration of the hydrogen atoms, respectively.

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.

Addition of α,α-dichloropropionitrile to unsaturated compounds under conditions of metallocomplex initiation

Abstractα,α-Dichloropropionitrile reacts with unsaturated compounds in the presence of complex initiating systems based on metal carbonyls. The systems based on iron pentacarbonyl are the most efficient.

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.