Sulfones reductions

SRP [Sulfonation-Reduction-Peroxide] A pulp-bleaching process which combines reduction with sodium borohydride and oxidation with hydrogen peroxide. Developed by Atochem in 1991 and licensed to Morton International, Chicago. 

Modified one-pot Julia olefination to give predominantly ( )-olefins from het-eroarylsulfones and aldehydes. A sulfone reduction step is not required. 

Whereas oxidation leaves the fused thietane derivative 218 intact by giving the corresponding sulfone, reduction produces the 4-isopropyl-l,l-diphenyl-bicyclo[4.1.0]hept-l-ene (219) by extrusion of sulfur (Eq. 58). The general oxidation procedure to convert thietanes to their sulfones comprises refluxing with peracetic acid. 

Sulindac 90 93 (and high for metabolites) 7-8 (16.4 sulfide) <1% of sulindac dose appears as active sulfide metabolite Yes sulindac and sulfone undergo extensive enterohepatic circulation relative to sulfide Extensive in liver - oxidation to sulfone, reduction to sulfide and glucuronidation Sulindac sulfide (parent is prodrug)... 

The plant required for the manufacture of dyes usually depends on unit processes. The unit processes such as nitration, sulfonation, reduction, and diazotization are treated extensively in the textbooks of organic chemistry and will not be included here. The general operation sequences in dye and intermediate manufacture are shown in Fig. 8.1. 

A disadvantage of this procedure is that reductive cleavage of the epoxy sulfones leading to trisub-stituted alkenes, e.g. (95), is not stereoselective. However, formation of disubsituted alkenes follows the trends found in the standard Julia alkenation in that rrani-alkenes are favored (equation 24) and proximate branching increases the stereoselectivity (equation 25). Unlike the standard Julia alkenation, the stereochemistry of the epoxy sulfone reductive elimination depends on the stereochemistry of the precur-... 

Desulfuration a-alkylation of -keto sulfones. Reductive alkylation of sul-fones is routinely carried out by a-alkylation of the enolate followed by desulfuration (Al/Hg). It can also be effected in one pot by desulfuration with lithium in liquid ammonia, which generates an enolate that can be alkylated. The yield is markedly enhanced by conversion of the lithium enolate to an alkylstannyl enolate by addition of BusSnCl with HMPT as cosolvent. 

Laboratory Studies. A variety of laboratory studies have been performed including degradation rate studies with actual samples from the saturated and unsaturated zones, oxidation mechanism studies, saturated zone degradation mechanism studies, potential for sulfoxide or sulfone reduction studies, and distilled water hydrolysis studies. The experimental methodology in these experiments varied according to the study objectives. 

Platinum catalysts modified by cinchona alkaloids have been developed for asym metric hydrogenation of a-keto acetals " and a-keto esters, and the Ru complex of chiral 2-(MeO)BIPHEP 97 has been developed for P-keto sulfone reduction. ... 

Reduction-decyanation. wc-Cyanohydrins can be converted to alkenes by conversion to a methylthiomethyl ether followed by oxidation to the sulfone. Reduction of this derivative with sodium naphthalenide results in an alkene... 

Sodium amalgam Hydrocarbons from sulfones Reductive cleavage... 

The one-port olefination of Sylvestre Julia is operationally simpler and more amenable to scale up than the classical y4-step variant originally reported by Marc Julia. This reaction consists of the replacement of the phenyl sulfone moiety traditionally in the classical reaction, with different heteroaryl sulfones, such as benzothiazol-2-yl (BT, 5) sulfone. This allows the direct olefination process and eliminates the sulfone reduction step. The stereochemistry of the reaction in the synthesis of 1,2-disubstituted alkenes is dependent on the base and solvent. 

SCHEME 22.3. Stereoselective sulfone reductive eliminations (NaHTe orSml2 ). 

Fmoc-based solid-phase glycopeptide synthesis is compatible with the standard linkers (handles) widely used in peptide synthesis, such as Rink amide, Wang, SASRIN (mild acid cleavage), 2-chlorotrityl chloride (protected peptide acid), and Sieber (protected peptide amides). For combinatorial one-bead one-compound studies, both the safety-catch amide linker (SCAL, stable to both acid and base until sulfone reduction) [24] and the photocleavable linker 4-[4-(l-aminoethyl)-2-methoxy-5-nitrophenoxy] butyric acid [25 ] have been successfully applied. These linkers are suitable for displaying the frilly deprotected glycopeptides on bead while allowing their nondestructive recovery after bead assay. Concerning... 

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