Sulfur compounds adducts

Addition compounds form with those organics that contain a donor atom, eg, ketonic oxygen, nitrogen, and sulfur. Thus, adducts form with amides, amines, and A/-heterocycles, as well as acid chlorides and ethers. Addition compounds also form with a number of inorganic compounds, eg, POCl (6,120). In many cases, the addition compounds are dimeric, eg, with ethyl acetate, in titanium tetrachloride-rich systems. By using ammonia, a series of amidodichlorides, Ti(NH2) Cl4, is formed (133). 

The thieno unit of thienothiepin 1 reacts with iV-phenylmaleimide at 150 C to give the Diels-Alder exo-product 2, with the loss of sulfur.71 Furanothiepin 3 (X = S) and its corresponding 5-oxide or 5,5-dioxide react readily with the same dienophile at room temperature, but in different ways. While the parent compound 3 and its oxide (X = S, SO) form the cycloadduct 4 with loss of sulfur, the dioxide gives a stable Diels-Alder adduct 5 (mixture of endojexo-isomers) which, upon heating above 100 C, loses sulfur dioxide to provide the sulfur-free adduct.70... 

Sulfur compounds have also been widely studied as activating agents for polyesterification reactions. p-Toluenesulfonyl chloride (tosyl chloride) reacts with DMF in pyridine to form a Vilsmeir adduct which easily reacts with carboxylic acids at 100-120° C, giving highly reactive mixed carboxylic-sulfonic anhydrides.312 The reaction is efficient both for aromatic dicarboxylic acid-bisphenol312 and hydroxybenzoic acid314 polyesterifications (Scheme 2.31). The formation of phenyl tosylates as significant side products of this reaction has been reported.315... 

The thione group of dithiazolethiones is a very reactive heterodipolarophile. In Scheme 18 are given cycloadditions with nitrile oxides <67BSF2239>, diphenylnitrilimine, and ethyl azidoformate <85JCS(P1)1205>. The primary adducts are spiro derivatives, but only compound (131), which is obtained from nitrile oxides is isolable at low temperature. All are decomposed to give respectively compounds (132)-(134) and occasionally nitriles and sulfur. Compound (134) reacts further with nitrilimine affording compound (135) which is also isolated. 

A number of Meisenheimer adducts from the reaction of selenophene derivatives 141, which are analogs of series 121, with methoxide ion have been investigated and characterized.I<9- 81 Their formation is generally even easier than that of the related sulfur compounds. 

Figure 2. Radioactivity chromatogram of sulfur compounds derivatized with monobromobimane. The reversed-phase HPLC separation is based on the hydrophobic properties of the bimane-sulfur adducts but peak area is based on "S-radioactivity of the compounds. At time 0 sulfite and thiosulfate impurities are present before addition of the hepatopancrease tissue homogenate. This was a 60 min experiment to determine the sulfide detoxifying functions of the hepatopancrease of the hydrothermal vent crab Bythograea thermydron. During this time the proportion of radioactivity in sulfide rapidly decreases and thiosulfate and sulfate accumulate as end products. Two intermediates, pi and p2 accumulate then decrease during the experiment. The two intermediates are believed to be polysulfides based on similar elution times of polysulfide standards. (Figure is the unpublished chromatograms from the data in Vetter et al. (24)-) continued on next page.

In summary, it is the sensitivity, broad reactivity with reduced sulfur compounds, and the stability of the bimane-sulfur adducts that makes the bimane-HPLC method superior for the kinds of experiments which we are engaged in. The method should find increasing usage among marine scientists who wish to store and analyze at a later time large numbers of samples. 

Another sulfur allotrope - cyclodecasulfur (Sio) - also reacted with norbomene under milder conditions to furnish the trithiolane 59 (R = H) as the unique reaction product in 85% yield <1999TL7961>. Similarly, the reaction of S10 with norbornadiene produced a trithiolane adduct 60 in good yield as well as a new bis-sulfurated compound 61 (Equation 21) <1999TL7961>. Reactions with Sg under the same conditions produced only traces of the expected products. 

Re has recently come to the forefront in liquid phase oxidation catalysis, mainly as a result of the discovery of the catalytic properties of the alkyl compound CH3Re03 [methyltrioxorhenium (MTO)]. MTO forms mono-and diperoxo adducts with H2O2 these species are capable of transferring an oxygen atom to almost any nucleophile, including olefins, allylic alcohols, sulfur compounds, amides, and halide ions (9). Moreover, MTO catalysis can be accelerated by coordination of N ligands such as pyridine (379-381). An additional effect of such bases is that they buffer the strong Lewis acidity of MTO in aqueous solutions and therefore protect epoxides, for example. 

The activity of sulfur towards platinum complexes has led to investigation of so-called rescue agents to ameliorate the side effects of platinum therapy, without compromising its anti-tumor activity. These nucleophilic sulfur compounds include sodium thiosulfate (STS), sodium diethyldithio-carbamate (Naddtc), (S)- 2-[(3-aminopropyl)amino]ethyl phosphorothioic acid (WR-2721, Ethyol , amifostine), glutathione (GSH), methionine, thiourea, cysteine, -acetylcysteine, penicillamine, biotin, sulfathiazole, sodium 2-mercaptoethanesulfonate (mesna), and its dimer (di)mesna (BNP-7787). The protective effect of these compounds is either due to prevention, or reversal of Pt-S adducts in proteins. Some of the more promising of the above-mentioned compounds (see Fig. 1) will be discussed below. 

Although charge transfers generally involve organics, iodine adducts of metal complexes are known. An example is [CpMo(NB u ) (fi-S) I2]21 where there is an I—I—S bond similar to those found for organic sulfur compounds such as 1,4,7-trithiacyclononane.11... 

Carbene adducts of a range of sulfur compounds have also been isolated. Carbene (1) (R = i-Pr, R = Me) reacts with sulfur dichloride or thionyl chloride to yield the hyperva-lent sulfur derivatives (118) and (119). Similarly, reaction of carbene (2) (R = r-Bu) with SO2 led to the formation of the 1 1 adduct (2)-SO2 (120). In contrast, reaction of carbene (1) (R = i-Pr, R = Me) with SO2CI2 affords the 2-chloro-l,3-diisopropyl-4,5-dimethylimidazohumchlorosul-fite salt (121). A carbene adduct of SO3 (122) can then be isolated through hydrolysis of (121) in the presence of cyanide. 

Acyclic alkenic sulfur compounds have also been obtained via pyrolytic rDA reactions. A general route to thioacrylamides utilizing rDA reactions under FVP conditions has been developed. The rDA reaction of the appropriate adducts yields thioacrylamide, V-methylthioacrylamide and NA -dimethyl-thioacrylamide in approximately quantitative yield (equation 13). The high reactivity of these a,3-unsaturated thioamides had previously limited their availability. a,3-Unsaturated acyclic chio-ketones such as (17) were prepared via a rDA reaction using a FVP technique. These highly reactive species dimerize to 4//-l,3-dithiins (18) on warming to-60 °C (equation 14). ... 

Adducts from acid amides and sulfur compounds... 

Assays for several other potential urinary analytes have been developed, but the analytes have yet to be confirmed in human exposed samples. N7-(2-hydroxyethylthioethyl) guanine is a breakdown product from alkylated DNA that has been observed in animal studies. Fidder et al. (1996a) developed both a GC-MS method that requires derivatization of the analyte and also a LC-MS-MS method that can analyze the compound directly. Other possible urinary analytes are an imidazole derivative formed from the reaction of sulfur mustard with protein histidine residues (Sandelowsky et al., 1992) and sulfur mustard adducts to metallothionien (Price et al., 2000). 

The powerful oxidizing action of sulfur trioxide can be overcome by using the sulfur trioxide addition compounds mentioned above (page 612) their activity in sulfonation depends on their stability.167 Disulfur hexaoxide or its adducts to mineral acids (e.g., H2S207) are more powerful sulfonating agents than the stable adducts to dioxan55,101 or tertiary amines very mild conditions can be used with the latter 172 compounds that are especially sensitive to acids can be sulfonated by the pyridine-sulfur trioxide adduct without decomposition. 

Heterocyclic compounds, in particular, are readily sulfonated by the pyridine-sulfur trioxide adduct 2-pyrrolesulfonic acid is formed from pyrrole,174 and 5-acetyl-3-pyrrolesulfonic acid from 2-acetylpyrrole.175... 

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