Halogenation with thiols

As with the halogens, the thiols, phosphines, silanes, and germanes undergo photoaddition to olefins via homolytic cleavage. Representative examples follow a24 130) ... 

Nucleophilic substitution of halogens in the ring or in side chains have been used for the synthesis of various derivatives of tellurophene. The reaction of 2-iodotellurophene with thiols catalyzed by Cu(i) ions gives rise to 2-organylthiotellurophenes 13 in 77-90% yields (Equation 3) <2005TL2647>. 

Taking this result into account, we have developed an efficient enzymatic route catalyzed by FruA in which the acceptor substrate is a commercially available 2-haloacetaldehydes (chloro- or bromo-) 19 yielding 5-halo-D-xylulose after dephosphorylation catalyzed by acid phosphatase (see Section 18.2.3.1). The thiol was introduced after the enzymatic step by displacement of halogen with NaSH, to... 

The displacement of halogen from phosphonic dihalides with thiols in the presence of an appropriate base leads to 5,S-diesters rather than (9,5-isomers (equation 30 Z = 0)2-7374,375 gych a reaction has been employed in the determination of the enantiomer composition of chiral thiols. The NMR spectra for a series of phosphonodithioates 163 (Z = O, R = Me, Ph, PhCH2) and also for analogous trithiophosphonates 163 (Z = S, R = Me or Ph) in which the group R is derived from a chiral thiol, showed that the best separation of P NMR signals for the diastereoisomeric forms was achieved when R = Me. Displacement reactions which involve the loss of chlorine from R2P(Z)C1 (Z = or Se ). RP(0)(SR )CP and RP(S)(NHR )C1 by thiols in the presence of a tertiary amine base, and many more, are widely exemplified. 

Bimane derivatives containing active halogen react with thiol compounds to form fluorescence thioet-hers. This reaction proceeds under relatively mild conditions, i.e., pH 8 at room temperature in 5 min. Monobromobimane and monobromotrimethyl-aminobimane as precolumn derivatization reagents... 

Several positive halogen compounds, ZHal, like N-halo-succinimide N-chlorobenzotriazole, dichloroiodoben2ene, etc., react with thiols to give sulphenyl haUdes or disulphides depending on the relative ratios of the reagents (equations 46 and 47). 

Literature reveals that in the oxidative cyclization of aldeltyde and o-phenylene-diamine, the formation of the required 2-aiyl-l/f-benzimidazole is accompanied by the occurrence of 1-benzylated 2-aryl-1/f-benzimidazoles as side products [46], and sometimes these disubstituted derivatives have been isolated as the main product [47, 48]. The present protocol gives 2-aryl-1/7-benzimidazole selectively. Further, we extended our studies on oxidative reactions of aldehydes with o-aminothiophe-nol. Although thiols are good nucleophiles and SET agents [49], in present studies, no substitution of the halogen atom or the nitro group, dealkylation/debenzoy lation, took place as reported earlier [50-52]. Fmiher, the dithioacetal formation is a common reaction of aldehydes with thiols [53] no competitive dithioacetal formation was observed imder the present conditions. Doping of Mn promotes the activity and... 

In another study. Turner and Battershell have considered the relative influence of chemical reactivity, vapor pressure, and oil/water partition coefficients (obtained from R j values ) on the fungicidal activity of a series of halogenated iso-phthalonitriles. They obtained excellent correlations (r = 0.96 and 0.94) between biological activity and the reactivity of the compounds with a model thiol compound and suggested that the mode of action involves reaction with thiol groups. ... 

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