Halides cyclic, reduction

Reaction with Sulfonyl Halides. Arylsulfonyl halides undergo reductive dimerization to form the corresponding disulfides (eq 35). Alkylsulfonyl halides, however, undergo this process under somewhat more vigorous conditions. Although sulfones generally do not react with TMS-I, certain cyclic sulfones are cleaved in a manner analogous to lactones. ... 

Reductive amination of dihydropyran (which may be regarded as the dehydration product of the cyclic acetal of 5-hydroxy-pentanal) in the presence of isopropylamine and a trace of acid affords the aminoalcohol, 96. Treatment of this compound with thionyl chloride affords the haloamine, 97. Alkylation of the quinoline, 92, with this halide yields pentaquine (98). ... 

Cyclic alkane derivatives, alkyl halide reduction, 29-31... 

Cyclic voltammetry was used to monitor the mechanism for (TPP)Rh(R) formation according to Equation 3 where RX is a terminal alkyl halide. The current for reduction of electrogenerated (P)Rh(R) or (P)Rh(RX) species is a measure of the concentration of this product at the electrode surface, and hence a measure of its rate of formation. The current must be standardized for experimental factors such as scan rate, initial concentration of [(TPP)Rh(L)J+cr (or other initial Rh(III) species), electrode area, and concentration of the alkyl halide reactant. 

An early example of such an approach is found in the reduction of butyl halides in a nonprotic solvent.47 The cyclic voltammetry of these compounds (Figure 2.44) suggests the mechanism depicted in Scheme 2.38. The first reaction leading directly to the butyl radical is the dissociative... 

Fig. 9 Electrochemical reductive cleavage of aryl halides in a poor H-atom donor solvent. Cyclic voltammetry as a function of the scan rate, v. E, Electrode potential i, current. Reduction (cathodic) currents are represented as being upwards.

The experimental kinetic data obtained with the butyl halides in DMF are shown in Fig. 13 in the form of a plot of the activation free energy, AG, against the standard potential of the aromatic anion radicals, Ep/Q. The electrochemical data are displayed in the same diagrams in the form of values of the free energies of activation at the cyclic voltammetry peak potential, E, for a 0.1 V s scan rate. Additional data have been recently obtained by pulse radiolysis for n-butyl iodide in the same solvent (Grim-shaw et al., 1988) that complete nicely the data obtained by indirect electrochemistry. In the latter case, indeed, the upper limit of obtainable rate constants was 10 m s", beyond which the overlap between the mediator wave and the direct reduction wave of n-BuI is too strong for a meaningful measurement to be carried out. This is about the lower limit of measurable... 

Phenylacetylenes (3 mol) react with Te02 (1 mol) and excess of lithium halide in refluxing HOAc to produce 3-halobenzotellurophenes via the addition of a Te(IV) acetate halide to the triple bond, cychzation (probably by loss of HOAc) and reduction of the Te(IV) cyclic product to 3-halobenzotellurophene by an excess of the phenylacetylene. Owing to isolation facihties, the product is converted into the crystalhne dichlorides that is reduced to the benzotellurophenes. °... 

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