Allylic substitution kinetic study

In basic aqueous media, a kinetic study of the reaction between stannate(II) ions and alkyl halide shows that mono- and disubstituted organotin compounds are formed (Eq. 6.12a).27 The monosubstituted organotin compound is obtained after a nucleophilic substitution catalyzed by a complexation between the tin(II) and the halide atom. The disubstituted compound results from an electrophilic substitution coupled with a redox reaction on a complex between the monosubstituted organotin compound and the stannate(II) ion. Stannate(IV) ions prevent the synthesis of the disubstituted compound by complexation. Similarly, when allyl bromide and tin were stirred in D2O at 60° C, allyltin(II) bromide was formed first. This was followed by further reaction with another molecule of allyl bromide to give diallyltin(IV) dibromide (Eq. 6.12b).28... 

Kinetic studies of 3a, 3b, and 3c have provided experimental evidence that a cyclopropyl diradical is an intermediate. The product composition reveals a temperature dependence that implicates an intermediate. These compounds undergo both cis-trans isomerization and di-Tr-methane rearrangement on direct irradiation and mainly cis-trans isomerization when photosensitized (triplet) by benzophenone. The quantum yield of the di-Tr-methane rearrangement increases dramatically with substitution at the allylic position. 

Meisenheimer et were the first to study the kinetics of allylic ester isomerizations. They followed the isomerization of a-phenylallyl p-nitroben-zoate and a-phenylallyl 3,4,5-tribromobenzoate to the corresponding cinnamyl benzoates by a tedious analytical procedure involving use of melting point-composition diagrams. They observed that isomerization of the molten esters at 137°C is autocatalytic due to partial slow decomposition of the esters to substituted benzoic acids and unidentified products, and demonstrated that the reaction is catalyzed by added benzoic acids. The rate law for these reactions is... 

The lability of allylic iodides and their sensitivity to free radical-induced isomerization, polymerization, and decomposition reactions has discouraged kinetic studies of their substitution and isomerization reactions. 

It is the metal complex precursor with allyamines for asymmetric allylic substitutions for resting state and kinetic studies [cf Markovic Hartwig Chem Soc 129 11680 2007]. 

When a racemic allylic substrate is employed in an enantioselective substitution reaction, one of the two substrate enantiomers may react more quickly than the other. This effect is a kinetic resolution and has been noted reasonably often in enantioselective allylic substitution reactions. Several studies on kinetic resolution have been reported, - and a few highlight reactions are noted in Scheme 45. These include recovery of unreacted cy-clohexenyl acetate 92, as well as the tetraacetate 225. Kinetic resolution has also been observed in allylic snbstitution using a snlfinate nucleophile (Li02STlu) with allyl acetate... 

Kinetic studies have been carried out on the reactions of a variety of substituted w-allylcobalt tricarbonyl derivatives with triphenylphosphine 242). The rates of these reactions were found to be independent of phosphine concentration above 0.06 M. Substituting the hydrogen atom on the center carbon atom of the three carbon atoms of the w-allyl system with either... 

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