Alcohols sulfones, cyclic

Reaction with Thiocarboxylic Acids, Phosphoric Acids, Sulfonic Acids, and their Derivatives. Thiocarboxylic acids, - dithiocarboxylic acids, and dimethyldithiocarbamic acid zinc salt, as well as various phosphorus oxyacids and phosphorus thioacids, can also be utilized. a,o)-Mercapto alcohols form cyclic thioethers whereas thiols react with both DEAD and TPP-DEAD to form disulfides. 2-Mercaptoazoles also react with alcohols in the presence of DEAD and TPP. Although arenesulfonic acids do not enter into the reaction, a combination of DEAD-TPP with methyl p-toluenesulfonate as a nucleophile carrier gives the corresponding alkyl sulfonates (eq 14). Altema-... 

The reaction of the enamines of cyclohexanones with a,ft-unsaluraled sulfones gives mixtures resulting from attack of the enamine at the a- and /(-carbons of the oc,/ -unsaturated sulfone. The ratio of x- and /1-adducts is dependent upon the reaction solvent, the geometry and structure of the sulfone1 4. The diastereoselectivity of these reactions is also poor. The reaction of lithium enolates of cyclic ketones with ( )-[2-(methylsulfonyl)ethenyl]benzene, however, gives bicyclic alcohols, as single diastereomers, that result from initial -attack on the oc,/ -unsaturated sulfone5. 

Addition of methyllithium to a cyclic /i, y -epoxy-a,/i-unsaturated sulfone gave predominately the m-alcohol as product20. 

The final example in this section is the synthesis of a tristetrahydrofuran 2-606 described by the group of Rychnovsky [313]. Here, the tris(sulfate) 2-605 was converted into 2-606 by simply heating it in a mixture of MeCN and H20 (Scheme 2.138). The domino reaction is most likely initiated by deprotection of the primary alcohol, which then attacks the adjacent sulfonate unit in a SN2-type manner to afford the first furan moiety. Under the reaction conditions the formed acyclic sulfate is hydrolyzed affording a free secondary alcohol which then attacks the next adjacent cyclic sulfate unit. Overall, the SN2/hydrolyzation sequence proceeds three times to finally provide the poly(tetrahydrofuran) 2-606 as a single isomer in 93 % yield. 

Wilkinson s catalyst has also been utilized for the hydroboration of other alkenes. Sulfone derivatives of allyl alcohol can be hydroborated with HBcat and subsequently oxidized to give the secondary rather than primary alcohol. This reactivity proves to be independent of substituents on the sulfur atom.36 Similarly, thioalkenes undergo anti-Markovnikoff addition to afford a-thioboronate esters.37 The benefits of metal-catalyzed reactions come to the fore in the hydroboration of bromoalkenes (higher yields, shorter reaction times), although the benefits were less clear for the corresponding chloroalkenes (Table 3).38,39 Dienes can be hydroborated using both rhodium and palladium catalysts [Pd(PPh3)4] reacts readily with 1,3-dienes, but cyclic dienes are more active towards [Rh4(CO)i2].40... 

Sulfenoetherification. The reagent in combination with trifluoromethane-sulfonic acid converts suitably unsaturated alcohols into five- to seven-membered cyclic ethers. The cyclization is considered to involve an intermediate episulfonium ion. 

Li et al. (1997) have discussed the use of catalytic antibodies to control the reactivity of carbocations. At an entry level, the acyclic olefinic sulfonate ester [72] is converted into the cyclic alcohol [73] (98%) using antibody 4C6 raised to hapten [73] with only 2% of cyclohexene produced (Appendix entry 15.1) (Li et al, 1994). 

The Pd-catalyzed allylic alkylation of sulfinate ions, thiols, and thiocarboxylate ions with racemic cyclic and acyclic allylic esters in the presence of bisphosphane BPA generally provides for an efficient asymmetric synthesis of allylic sulfones, sulfides, and thioesters. The Pd-catalyzed rearrangements of allylic sulfinates and allylic O-thiocarbamates, both of which proceed very efficiently in the presence of BPA, are attractive alternative ways to the asymmetric synthesis of allylic sulfones and allyUc thioesters also starting from the corresponding racemic alcohols. 

We have put forward (J. Am. Client. Soc. 2004, /26, 13900) an alternative approach to the enantioselective construction of cyclic quaternary centers. Addition of phenylacetylene to cyclopentanone followed by dehydration and Shi epoxidation gave the epoxide 10. Opening of the epoxide with allylmagnesium chloride proceeded with inversion, to give II. The alcohol 11 can also be carried on to bicyclic products, exemplified by the sulfone 12. 

Because of the special structural requirements of the resin-bound substrate, this type of cleavage reaction lacks general applicability. Some of the few examples that have been reported are listed in Table 3.19. Lactones have also been obtained by acid-catalyzed lactonization of resin-bound 4-hydroxy or 3-oxiranyl carboxylic acids [399]. Treatment of polystyrene-bound cyclic acetals with Jones reagent also leads to the release of lactones into solution (Entry 5, Table 3.19). Resin-bound benzylic aryl or alkyl carbonates have been converted into esters by treatment with acyl halides and Lewis acids (Entry 6, Table 3.19). Similarly, alcohols bound to insoluble supports as benzyl ethers can be cleaved from the support and simultaneously converted into esters by treatment with acyl halides [400]. Esters have also been prepared by treatment of carboxylic acids with an excess of polystyrene-bound triazenes here, diazo-nium salts are released into solution, which serve to O-alkylate the acid (Entry 7, Table 3.19). This strategy can also be used to prepare sulfonates [401]. 

The at complex from DIB AH and butyllithium is a selective reducing agent.16 It is used tor the 1,2-reduction of acyclic and cyclic enones. Esters and lactones are reduced at room temperature to alcohols, and at -78 C to alcohols and aldehydes. Acid chlorides are rapidly reduced with excess reagent at -78 C to alcohols, but a mixture of alcohols, aldehydes, and acid chlorides results from use of an equimolar amount of reagent at -78 C. Acid anhydrides are reduced at -78 C to alcohols and carboxylic acids. Carboxylic acids and both primary and secondary amides are inert at room temperature, whereas tertiary amides (as in the present case) are reduced between 0 C and room temperature to aldehydes. The at complex rapidly reduces primary alkyl, benzylic, and allylic bromides, while tertiary alkyl and aryl halides are inert. Epoxides are reduced exclusively to the more highly substituted alcohols. Disulfides lead to thiols, but both sulfoxides and sulfones are inert. Moreover, this at complex from DIBAH and butyllithium is able to reduce ketones selectively in the presence of esters. 

Allylic alcohols are reduced with lithium or sodium in ammonia, or low molecular weight amines either with or without alcohols. The thermodynamically more stable product is often formed, leading to rearrangement in some cases (equation 71). Methyl and cyclic ethers are similarly reduced (equations 72 and 73), as are allylic acetates, halides and epoxides (equation 74 and 75). 7.i08 Benzylic and allylic sulfides and sulfones are readily reduced to hydrocarbons using lithium or sodium in alcoholic solvents or in amines. " Allylic sulfones are reduced in a similar manner (Scheme 11)," either with or without migration of the double bond, depending on the reaction conditions used. 

The applications of ruthenium tetroxide range from the common types of oxidations, such as those of alkenes, alcohols, and aldehydes to carboxylic acids [701, 774, 939, 940] of secondary alcohols to ketones [701, 940, 941] of aldehydes to acids (in poor yields) [940] of aromatic hydrocarbons to quinones [942, 943] or acids [701, 774, 941] and of sulfides to sulfoxides and sulfones [942], to specific ones like the oxidation of acetylenes to vicinal dicarbonyl compounds [9JS], of ethers to esters [940], of cyclic imines to lactams [944], and of lactams to imides [940]. 

The same maleic acid macrolide was also used to produce bolaamphiphiles with two different head groups in high yield. For this purpose, the macrolide was first dissolved in 2-propanol and reacted with an alkaline solution of 2-mercapto-succinic acid. The solvent was then evaporated and the residue extracted with acetone to remove a minimal percent of the remaining macrolide. The product, which contained only one mercaptosuccinic acid substituent, was redissolved in hot 2-propanol/water 4 1 and then sodium bisulfite added. A bolaamphiphile with a large dicarboxylic acid head group and a small sulfonate head group was thus obtained in an almost quantitative yield . Of course, it is also possible to esterify the maleic acid with bolaamphiphile alcohols in order to obtain asymmetric, non-cyclic bolaamphiphiles (Scheme 2.10). 

The aim of this section is to show how cyclic precursors can serve as an appropriate starting material for the construction of open-chained or monocyclic intermediates with defined regio- and/or stereo-specifity. The nucleofuge usually is halide or sulfonate and the electrofuge an alkoxide, generated from an alcohol by base or from a keto group by attack of a nucleophile. 

Sulfonyl carbanions are even more stable than sulfinyl carbanions and are consequently of greater significance in synthesis. They can be alkylated and acylated at the a-carbon atom using organolithium bases, and cyclic sulfones can be formed by intramolecular alkylation, (see Chapter 10, p. 202). Sulfonyl carbanions (73) also react with terminal epoxides, and this reaction is applicable for the synthesis of unsaturated alcohols (74) (Scheme 33). 

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