Martin sulfurane

The tetravalent sulfur reagent Martin sulfurane permits dehydration of alcohols under 

The reagent is expensive, given the fluorinated alkoxy (RpO) ligands, but is ideally suited for valuable and/or sensitive substrates. It s prepared from diphenyl sulfide and potassium l,l,l,3,3,3-hexafluoro-2-phenyl-2-propanolate as follows  

Write out mechanisms for the reactions involved in the synthesis of Martin sulfurane, reaction 6.111. 

The mechanism of action of Martin sulfurane is shown below for the dehydration of cyclohexanol  

As with SF4 and related reagents, the alcohol coordinates to the tetravalent sulfur center, followed by stepwise departure of two RpOH molecules. In the mechanism proposed below, departure of the second RpOH also results in the alkene product  

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Step 2 Alcohol dehydration with Ph2S[OC(CF3)2Ph]2 (Martin sulfurane reagent). 

The Martin sulfurane is an excellent reagent for the rapid dehydration of tertiary alcohols.12 Mechanistically, the dehydration involves ligand exchange around sulfur, diphenylsulfonium ion formation, and El elimination of diphenylsulfoxide to give the alkene (Scheme 8.11). 

What is the mechanism of the Martin sulfurane step k leading to compound 11 ... 

L-enantiomer [137]). The final reduction step with cyanoboro hydride concluded the sequence to yield the C-arylglycoside 178. The corresponding C-aryl-glycals can also be prepared by water elimination of the hemiacetal using the Martin sulfurane (Ph2S[OC(CF3)2Ph])2) [138]. 

A more inorganic example might be the ionization of Martin sulfurane, a rather fancy tetravalent-sulftir-based dehydrating agent (discussed in Section 6.13) ... 

Martin sulfurane can dehydrate vicinal diols to epoxides, as shown below ... 

Sulfur tetrafluoride and aminosulfur trifluorides are important fluorinating agents that typically operate via a non-redox mechanism. Similarly, Martin sulfurane is a tetravalent sulfur-based dehydrating agent for alcohols, which also operates via a non-redox pathway. 

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