Methanesulphonyl chloride: esters from

Aryl sulphonyl chlorides may also be synthesized from the sulphinyl chloride, by oxidation with chlorine, in 80% yield573 (equation 146) or dimethyl sulphoxide574. Sulphinate esters may also be utilized as the precursor to sulphonyl halide via oxidative halogenation. For example, methyl methanesulphinate is converted to methanesulphonyl chloride in excellent yield at 0°C568. 

Treatment of (15R)-PGA2 methyl ester (208 R = Me, R = H) from coral with methanesulphonyl chloride and solvolysis of the resulting mesylate (212) in acetone-water gave the C-15-inverted product (213), which after acetylation [to (209b)] was similarly converted into PGE2 and PGF2 (Scheme 45). 

Esterification.—iVAWW -Tetramethylchloroformamidinium chloride, which is readily prepared from iVAWW -tetramethylurea and oxalyl chloride, is an efficient reagent for the esterification of carboxylic acids with alcohols yields of between 66 and 97% are obtained, and the method has also been applied to macrolide synthesis. A modified one-pot procedure for the esterification of carboxylic acids, using phenyl dichlorophosphate-dimethylformamide complex, has appeared. A simple method of activation of carboxylic acids, using methanesulphonyl chloride and triethylamine followed by addition of the alcohol and 4-dimethylaminopyridine, leads to esters in 57— 96% yield for thirteen examples. 0-Methylcaprolactim reacts with carboxylic acids to give methyl esters in 73—91 % yield for seven examples and 2-iodoethyl esters are prepared from acyl chlorides, ethylene oxide, and sodium iodide. Transesterification, catalysed by titanium(iv) alkoxides, provides an effective method for synthesis of esters. Diethyl trichloromethylphosphonate reacts with carboxylic acids to give ethyl esters via transesterification, in 52 to 98 % yield. ... 

Syntheses of ( )-canadine, ( )-thalictricavine, ( )-corydaline, and berlambine have been achieved from dimethoxyhomophthalic anhydride (88). The anhydride reacts with hydrastinine (87 R R = CH2) and its dimethoxy-analogue (87 R = r2 = Me) to give the lactam acids (89 R R CH2) and (89 R = R = Me) the methyl esters of which, on reduction with lithium aluminium hydride, yield the alcohols (90 R R = CH2, R = CH2OH) and (90 R = R = Me, R = CH2OH). The conversion of these alcohols into their methanesulphonyl esters, followed by reduction with sodium borohydride, then affords ( )-thalic-tricavine(90 R R = CHa,R = Me) and( )-corydaline(90 R = R = R = Me). Oxidation of the lactam acid (89 R R = CH2) with lead tetra-acetate and copper(ii) acetate in acetic acid and dimethylformamide gives the unsaturated lactam berlambine (91), which can be reduced by lithium aluminium hydride in the presence of aluminium chloride to ( )-canadine (90 R R = CH2, R" = H). ... 

A further patent for the production of codeine, via codeinone, from thebaine has been published. " Codeine has been shown to be oxidized by manganese dioxide to 14-hydroxycodeinone the reaction is presumed to proceed via codeinone since 6-acetylcodeine is not affected by the same reagent. 6-O-Methanesulphonyl-dihydrocodeine has been shown to react with tetra-butylammonium fluoride, lithium chloride, and lithium bromide, with inversion at C-6, to give the related 6-halogeno-dihydrocodides, but when the ester is heated with sodium iodide in dimethylformamide the product is A -deoxycodeine (deoxycodeine-C) (143). Reductive amination of naltrexone with 2,2 -dihy-droxydiethylamine and sodium cyanoborohydride yields the 6-amino-compound (144 R = OH), which can be converted by carbon tetrachloride and tri-... 

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