Thiuram disulfides reagents

Lithium dibutylisopropylmagnesate proved to be quite efficient for the bromine-magnesium exchange of 5-bromo-2-picoline at —10 °C (Table 14) . The resulting picolyl-magnesium reagent reacted with electrophiles including thiuram disulfide (last entry). 

A convenient reaction of organolithium with easily available thiuram disulfides was reported by Gronowitz et al. [45], and the reaction of Grignard reagents with N,AT-dimethylthiocarbamoyl chloride was found [46] to be nicely catalysed by NiCl2(dppe) to afford thioamides. An analogous route with palladium[II] catalysis allowed Hartke et al. [47] to prepare a number of interesting a-acetylenic thioamides. 

Figure 2. HPLC-assay of NCp7 with thiuram disulfides. NCp7 was reacted with 6-fold excess of various thiuram disulfides at pH 7.0 for 10 min at 37 C. The products of the reaction were identified as follows I - unreacted p7 II - 3(S-S) p7 shaded peak is tetramethylthiuram disulfide other reagents were eluted later on chromatogram (not included).

In order to analyze the action of the thiuram disulfides on NC protein in whole virus, lOOOx concentrated cell-free HIV-l(MN) was incubated with 50 mM of thiuram disulfides for 60 min. The virus was then pelleted by centrifugation to remove reagents and was analyzed by western blot analysis with antibody against p7 (Fig. 6). Under non-reducing conditions the NC protein of untreated virus is a mixture of monomers, dimers, trimers and tetrameters (see Fig. 6, HIV-1 lane). These virus treated with thiuram disulfides showed NC antigen migrating above 200 kDa marker and in some cases the monomeric form of NCp7 was completely absent (tetraethyl-thiuram, tetraisopropylthiuram and dicyclopentamethylene-... 

Other reagents for the formation of TTF—S bonds include thiuram disulfides (93UP1) and di(phenylsulfonyl) sulfide (92TL1783) (Scheme 56). The use of SEM disulfide is referred to below. 

Indeed, this transformation has been developed into a procedure for the preparation of isothiocyanates from primary amines using hydrogen peroxide as the dehydrosulfurization reagent. It proceeds via the thiuram disulfide, although concentrations of the latter are always kept low (Fig. 8) (85). 

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