Sulfur-oxygen bond forming reactions

Sulfur - Oxygen Bond Forming Reactions S-0 bond 1... 

The synthesis of substituted tetrahydropyranylidene acetates such as 465 and 466 can be accomplished by TiCU-promoted carbon-carbon bond-forming reactions of ethyl glyoxylate, 3,4-dihydro-2/7-pyran 455, and oxygen or sulfur nucleophiles (Scheme 82). The reaction is an efficient three-component coupling process and the overall outcome of the reaction is dependent upon reaction temperature <1999TL4751>. 

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]. 

Most of the material presented in this section are reactions of sulfur trioxide. This compound is ambivalent and frequently forms a carbon-sulfur bond (true sulfonation), but it can form a carbon-oxygen bond as well. Examples of both types of bonding are included... 

Thiocarbamate (tc, RHNCSO-) is a monodentate ambidentate ligand, and both oxygen- and sulfur-bonded forms are known for the simple pentaamminecobalt(III) complexes. These undergo redox reactions with chromium(II) ion in water via attack at the remote O or S atom of the S- and O-bound isomers respectively, with a structural trans effect suggested to direct the facile electron transfer in the former.1045 A cobalt-promoted synthesis utilizing the residual nucleophilicity of the coordinated hydroxide in [Co(NH3)5(OH)]2+ in reaction with MeNCS in (MeO)3PO solvent leads to the O-bonded monothiocarbamate, which isomerizes by an intramolecular mechanism to the S-bound isomer in water.1046... 

Sulfation is the generation of an oxygen sulfur(IV) bond, where the oxygen is attached to the carbon backbone, in the most controlled manner possible, using some form of sulfur dioxide moiety. When sulfating alcohols, the reaction is strongly exothermic, Examples of feedstocks for such a process include alkenes, alcohols, or phenols. Unlike the sulfonates, which exhibit excellent stability to hydrolysis, the alcohol sulfates are readily susceptible to hydrolysis in acidic media, The sulfation of fatty alcohols and fatty polyalkoxylates has produced a substantial body of commercial detergents and emulsifiers. 

The SRN1 process has proven to be a versatile mechanism for replacing a suitable leaving group by a nucleophile at the ipso position. This reaction affords substitution in nonactivated aromatic (ArX) compounds, with an extensive variety of nucleophiles ( u ) derived from carbon, nitrogen, and oxygen to form new C—C bonds, and from tin, phosphorus, arsenic, antimony, sulfur, selenium, and tellurium to afford new C-heteroatom bonds. 

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