Synthesis alkyl sulfonate

The usual sulfone synthesis by displacement of halide by sulfmate is assumed to have a nucleophilic 8 2 mechanism However, in special cases of alkyl halides with additional, electron-withdrawing substituents a radical substitution pathway has been observed (equation 32). Correspondingly, substitutions under formation of sulfones take... 

Alkyl hydroperoxysilanes, preparation, 783 Alkyl hydrotrioxides, structural chemistry, 132 Alkyl iodides, dioxirane oxidation, 1158 Alkyl methyl sulfonates, alkyl hydroperoxide synthesis, 673... 

The basic malonic ester synthesis we have outlined can be modified. Often one can advantageously use different bases as, for example, potassium tert butoxide alkyl sulfonates instead of halides polar aprotic solvents like DMSO or DMF (Sec. 1.21). 

Of the activated alcohols described in Section 1.1.2.S.1, alkyl sulfonates ate convenient alkylating re-agents because they can be readily prepared and handled. The correct choice of sulfate-alcoholate combination is often crucial for successful ether synthesis. Thus, for the preparation of cholesteryl ethers from the tosyl derivative of cholesterol and alkoxides, the reaction must be carried out at 110 °C for 2.S h in a sealed tube. Alternatively, the sodium salt of cholesterol can be reacted with an alkyl mesylate at 80 °C for 1 h in DMF to give the corresponding ether in 62-68% yield. ... 

Alkyl halides and alkyl sulfonates have been generally used as alkylating reagents. An example of the conversion of an alcohol into a primary amine by the Gabriel synthesis is shown in Scheme 37. ... 

Alkylation of the hydroxy aromatic compound to the corresponding alkoxy aromatic compound may be performed in accordance with known alkylation procedures in which the hydroxy aromatic compound is reacted with an alkyl sulfate, alkyl halide or alkyl sulfonate in a suitable solvent, usually water, containing a base such as sodium hydroxide. Such reactions are shown at various places in the literature, as for ex. in Organic Synthesis, Col. Vol. II, page 619, 1943, in which veratraldehyde is prepared from vanillin. The iodide salt may, if desired, be recaptured subsequent to the alkylation reaction. 

Furthermore, several syntheses of a,p-unsaturated carbonyl compounds have involved the alkylation of suitably functionalized sulfones, followed by the base-promoted elimination of the sulfenate moiety on related alkyl sulfones bearing an oxygen atom at the -y-position (Scheme 106, entries b-d Scheme 110, entry c Scheme 105, entry b). - 46i Particularly interesting is the synthesis of nuciferal (Scheme 106, entry d) which involves sequential alkylation of y,-y-dioxy sulfones, deblocking of the acetal moiety and sulfenate elimination. In this and related reactions y, y-dioxy-a-metalloalkyl sulfone has played the role of a masked p-metallo-a,p-unsaturated carbonyl compound (M(>aC—C—C=0), which is not a directly available synthon. 

Internal alkylation takes place on reaction of a-haloalkyl alkyl sulfones with bases and produces epi-sulfones as intermediaries. These intermediates are usually unstable and provide alkenes by thermal extrusion of sulfur dioxide. This reaction, known as the Ramberg-Backlund rearrangement, has been widely used in synthesis and has been thoroughly reviewed (Scheme 107, entry e).36-3. 43<.473... 

The theimolysis of 2-substituted 2,5-dihydrothiophene 1,1-dioxides leads to ( ) conjugated dienes via cycloieversion followed by the concerted cheletropic extrusion of sulfur dioxide. The thermolysis of the a, -alkylated sulfone (96) gives the intennediate, which loses SO2 to give 1-dodecadien-l-yl acetate (98), a component of the sex pheromone of the red bollwoim moth. Tliis procediue has been extended to the thermolysis of a,3-dialkylated sulfones in order to obtain ( , )-1,4-disubstituted-1,3-dienes (equation 46). Similar processes have been used for the syntheses of alkaloids. The synthesis of an Elaeocarpus alkaloid, elaeokwine A (100), makes use of the retrodiene extrusion of sulfur dioxide to give the 1,3-diene intermediate (99) that is subsequently consumed by an intramolecular imino DA reaction (equation 47). o-Xylylene (102) has been generated by rDA expulsion of SO2 from benzo-fiised 3,6-dihy(ho-l,2-oxathiin 2-oxide (101). ... 

Among the different methods for the formation of C-C double bonds, the reductive elimination of (3-functionalized (mainly P-hydroxy or (3-carboxy) sulfones, is one of the most widely used ones in organic synthesis. The reductive elimination of (3-hydroxy sulfones and derivatives is the so-called Julia,94 or Julia-Lythgoe olefination reaction (Eq. 2). It usually involves a condensation between the anion of an alkyl sulfone and a carbonyl compound to afford a (3-hydroxy sulfone (Eq. 47). The metal alkoxide intermediate is typically transformed in situ into a carboxylic or sulfonic ester derivative, which is then reduced... 

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