Sulfur-nitrogen bond forming reaction

Sulfur - Nitrogen Bond Forming Reaction S-N bond 1... 

The use of hypervalent iodine reagents for heteroatom-heteroatom bond forming reactions is well established in the context of classical oxidation chemistry [1-11]. For example, oxidations of anilines to azobenzenes, thiols to disulfides, and sulfides to sulfoxides with aryl-A3-iodanes were documented decades ago [1-5]. During the last ten years, particular attention has also been given to oxidative transformations of compounds derived from heavier elements, including the interception of reaction intermediates or initially formed products with external nucleophiles. A second important development is the utilization of sulfonyliminoiodanes, ArI = NS02R, for heteroatom-nitrogen bond formation, especially for imidations of sulfur, selenium, phosphorus and arsenic com-... 

Xiang, Li, and coworkers used t-butyl hydroperoxide to form a carbon-centered radical a to the nitrogen of an amide 30. The carbon-centered radical can abstract a sulfur atom from a disulfide 31 to form a new C—S bond. This is one of the few transition metal-free C—S bond-forming reactions." ... 

Beyond C-C bond forming reactions, decarboxylative couplings have recently found application in regiospecific formations of carbon-halogen [82, 83], carbon-sulfur [84, 85], carbon-phosphorus [86, 87], carbon-nitrogen [88], and carbon-oxygen bonds [89]. 

Hydrogenolysis is analogous to hydrolysis and ammonolysis, which involve the cleavage of a bond induced by the action of water and ammonia, respectively. Chemical bonds that are broken by hydrogenolysis reactions include carbon—carbon, carbon—oxygen, carbon—sulfur, and carbon—nitrogen bonds. An example of hydrogenolysis is the hydrodealkylation of toluene to form benzene and methane ... 

Sulfamation is the formation (245) of a nitrogen sulfur(VI) bond by the reaction of an amine and sulfur trioxide, or one of the many adduct forms of SO. Heating an amine with sulfamic acid is an alternative method. A practical example of sulfamation is the artificial sweetener sodium cyclohexylsulfamate [139-05-9] produced from the reaction of cyclohexylamine and sulfur trioxide (246,247) (see Sweeteners). Sulfamic acid is prepared from urea and oleum (248). Whereas sulfamation is not gready used commercially, sulfamic acid has various appHcations (see SuLFAMiC ACID AND SULFAMATES) (249—253). 

Other side reactions that have been reported are cleavage of the carbon-nitrogen bond to form 24 and an aminyl radical 25 or scission of the tliiocarbonyl-sulfur bond to form a thiyl radical 26 and 27 (Scheme 9.I0). U 6 4 Thiocarbonyl-sulfur bond cleavage may be a preferred pathway in the case of primary dithioearbamates. 

This approach is used exclusively for the synthesis of the isomeric annelated isothiazoles and isoselenazoles to form the nitrogen-sulfur(selenium) bond and has been discussed in CHEC-II(1996) <1996CHEC-II(7)49>. A wide variety of oxidative cyclizations have been reported, some of which incorpotate an amination. Eor example, reaction of 47 with chloramine gives the corresponding isothiazolo[5,4-7]thiophene 40 (Equation 9) <2000P65>. 

One of the best known examples of reversibility in bond formation is the cross-linking of cysteine, a sulfur-containing amino acid, that affects tertiary structure in proteins and, ultimately, macroscale phenomena such as the degree of curl in hair. Other examples include the imine bond, formed by the reaction of an amine group with an aldehyde, and metal coordinate bonds to atoms such as nitrogen as found in many enzymes. 

Iron-sulfur proteins contain non-heme iron and inorganic (acid-labile) sulfur in their active centers as 4Fe-4S or 2Fe-2S or, in the case of rubredoxin, as one iron alone. The iron is always bonded to cysteine sulfur. They catalyze redox reactions between +350 and —600 mV (hydrogen electrode = —420 mV). They are usually of low molecular weight (6000-15,000 Daltons) but can form complex enzymes with molybdenum and flavin. They occur as soluble or membrane-bound proteins and catalyze key reactions in photosynthesis, oxidative phosphorylation, nitrogen fixation, H2 metabolism, steroid hydroxylation, carbon and sulfur metabolism, etc. They occur in all organisms so far investigated and may... 

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