Martin sulfurane reagent

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). 

To a solution of 20 g alcohol (43.5 mmol) in 400 mL CH2CI2 at room temperature was added Martin s sulfurane reagent until the completion of the reaction as monitored by TLC... 

The tetravalent sulfur reagent Martin sulfurane permits dehydration of alcohols under... 

The first indication of the chirality of sulfuranes was provided by the X-ray analysis of spirosulfurane 176 (192). This work clearly demonstrated the presence of enantiomeric pairs of 176 in the crystal lattice. In 1975, the optically active chlorosulfurane 177, the first example of an optically active tetracoordinate sulfurane, was synthesized by Martin and Balthazor (194,195) by the route indicated in Scheme 15. Reaction of (-)-(5)-menthyl benzenesulfinate 178 with the protected Grignard reagent 179 gave the corresponding sulfoxide alcohol (-)-(5>180 which was cyclized to the chlorosul-... 

Furukawa et al. have reported one of the most convenient methods to prepare various Martin s type sulfuranes as shown in Scheme 25 [61]. Thianthrene S-monoxide (33) was found to react with alkyl Grignard reagents affording the o,o -bis-Grignard reagent of diphenyl sulfide, which was converted initially into the corresponding diols 34 on treatment with aldehydes or ketones, and then to the Martin s sulfuranes 35 by treatment with tert-butyl hypochlorite. 

Martin s sulfurane (1) enables quick and efficient elimination of secondary and tertiary alcohols 2 to yield alkenes 3 along with production of diphenyl sulfoxide (4) and alcohol 5.1,2 This highly reactive dehydrating reagent is effective at room temperature and below, and reactions are often complete in less than one hour. Primary alcohols rarely react to yield alkenes and instead are transformed into ethers. The title reagent is available from numerous commercial sources and can be prepared in large quantities according to several published procedures.3... 

Although widely used as a dehydration reagent, Martin s sulfurane is also known to facilitate amide cleavage reactions,7 cyclic ether (including epoxide) formations,8 and sulfilimine syntheses.9 In the 1970s Martin demonstrated all of these transformations in his series of papers outlining the reactivity of the title sulfurane. 

Martin s sulfurane is frequently employed in organic synthesis and is an especially valuable reagent in natural product total syntheses. In this context, it has been used to produce acyclic alkenes and dienes along with a variety of cyclic alkenes. 

By far the most common cycloalkene generated using Martin s sulfurane is cyclohexene. Isolated six-membered ring alkenes and cyclohexenes in fused polycyclic systems are all generated with regularity using the title reagent. 

Martin s sulfurane has been used to prepare a variety of cyclopentenes for use in the total syntheses of complex natural products. Myers effectively employed the title reagent to prepare synthetic intermediates for use in his total synthesis of the neocarzinostatin chromophore.43 (For dehydrations to yield alkenes in the nine-membered ring of this compound, see Section 3.7.5.4.) One example is reaction of tertiary alcohol 86 to furnish alkene 87 in 93% yield. In Phillips s total synthesis of cylindramide A, he employed a conjugate addition-reduction-elimination sequence (88—>89) to generate the... 

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