Sulphonate esters synthesis

Nucleophilic substitution of toluene- -sulphonates (tosy-lates) and other sulphonic esters of secondary steroidal alcohols has received much attention, both in studies of reaction mechanisms, and also as a route for the conversion of alcohols into their epimers. One of the most important practical objectives has been the synthesis of 3a-hydroxy-5a-steroids, which include androsterone and a wide variety of metabolites of the steroid hormones, Tosylates of equatorial 3jS-alcohols (15) give 3a-alcohols or their derivatives (16) in acceptable... 

The Neber rearrangement of oxime sulphonate esters (equation 28) is a useful method for the synthesis of a-aminoketones78. The reaction is base catalysed and involves abstraction of the most acidic proton a to the oxime functional group, as exemplified by the exclusive formation of compound 40 in this rearrangement (equation 29). 

D. Synthesis of Isotopically Labelled Sulphonate Esters and Sulphates. . . 628... 

The reactions of lithiophosphide reagents with alkyl halides or sulphonate esters have continued to find wide application in the synthesis of new phosphines. A series of phosphino-ethers, e.g., (22), has been prepared from the reactions of chloromethyl-substituted ethers with lithium diphenylphosphide. " A one-step synthesis of macrocyclic phosphino-ethers and -thioethers (23) is afforded by the reactions of dilithio-organophosphides with bis(j8-chloroethyl)-ethers and -thioethers derived from ethane-1,2-diol and ethane-1,2-dithiol, respectively. " A new family of water soluble phosphonio-phosphine ligands (24) has been prepared by the reaction of a,o)-dihaloalkanes with one mole of lithium diphenylphosphide, followed by quatemisation of the intermediate w-haloalkylphosphine with trimethylphosphine. The new ligand system (25) has been prepared by the reaction of chloromethylbenzene-chromium tricarbonyl with... 

There has been substantial activity in the synthesis of 3-amino-2,3,6-trideoxy-hexoses and their di-A-methyl derivatives as a result of their wide occurrence in antibiotics. In a paper of substantial proportions, Bartner et alP have synthesized by standard reactions all four possible methyl 2,3,6-dideoxy-3-dimethylamino-a-D-hexopyranosides (and some /3-anomers) as well as the corresponding L-ribo isomer (L-megosaminide). Syntheses have been reported for D-ristosamine (3-amino-2,3,6-trideoxy-D-rz7 o-hexose) from methyl 2-deoxy-D-amfcmo-hexo-pyranoside and of the isomeric 3-amino-2,3,6-trideoxy-L-Jcy/o-hexose (1) from methyl 2,6-dideoxy-L- mZ>mo-hexopyranoside, using standard sequences involving azidej displacement of sulphonate esters for introducing the nitrogen. 

Synthesis of methyl 5-benzenesuIphonyl-3,7-dimethyl-9-(2, 6, 6 -trimethyIcycIo-hex-r-en-l -yl)nona-2,6,8-trienoate (C2o-sulphone ester 3)... 

In the preparation of various unsaturated amides, the dianion of -phenyl-2-(phenyIsulphonylmethyl)propenamide (49) proved to be a versatile synthon. Borohydride reduction of alkylation products of the dianion occurred in high yield to afford moderate overall yields of ,B-unsaturated amides.The dianion of the corresponding phenyl sulphide alkylated poorly giving small amounts of oth a- and y-alkylation products, whereas the sulphone-ester corresponding to (49) was found to be labile under the deprotonation conditions. Compound (49) was also employed in the development of a general strategy for the synthesis of 3,4-epoxy-2-methylene-alkanoic acid amides (Scheme 29). ... 

The reductive desulphurization of a cyclic sulphonic ester plays a primary role in a stereospecific synthesis of /3-santalene (Scheme 164). 

Sulphonyl Peroxides.—Continuing interest in this class of compound is a consequence of their value in aromatic sulphonoxylation and in their addition to alkenes to give sulphonate esters. A useful electrochemical preparation of bis(methanesulphonyl) peroxide from sodium methanesulphonate makes available a reagent for the synthesis of methanesulphonates of less reactive aromatic hydrocarbons. 

Sulphonates.—Synthesis of aryl arenesulphonates through arenesulphonoxylation of unactivated aromatic hydrocarbons can be accomplished using arenesulphonyl peroxides. Although other serviceable routes to sulphonate esters do not need to be documented here, since they are so well known, a procedure for the... 

Developments of standard uses of sulphonate esters in synthesis include the use of magnesium halides MgBrj " and Mgli" for conversion into alkyl... 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Syntheses of lactones and lactams The syntheses of sulphones, sulphoxides and cyclic sulphides... 

Methylenesulphones are more acidic than the simple esters, ketones and cyano compounds and are more reactive with haloalkanes [e.g. 48-57] to yield precursors for the synthesis of aldehydes [53], ketones [53], esters [54] and 1,4-diketones [55] (Scheme 6.4). The early extractive alkylation methods have been superseded by solidtliquid phase-transfer catalytic methods [e.g. 58] and, combined with microwave irradiation, the reaction times are reduced dramatically [59]. The reactions appear to be somewhat sensitive to steric hindrance, as the methylenesulphones tend to be unreactive towards secondary haloalkanes and it has been reported that iodomethylsulphones cannot be dialkylated [49], although mono- and di-chloromethylsulphones are alkylated with no difficulty [48, 60] and methylenesulphones react with dihaloalkanes to yield cycloalkyl sulphones (Table 6.5 and 6.6). When the ratio of dihaloalkane to methylene sulphone is greater than 0.5 1, open chain systems are produced [48, 49]. Vinyl sulphones are obtained from the base-catalysed elimination of the halogen acid from the products of the alkylation of halomethylenesulphones [48]. 

---