O-Detosylation

O-Detosylation 31,2 Deuteriation, total, of fatty acids 23, 642s31 Deuterio compds. 

Via intermediates O-Detosylation of nucleosides via epimerized cyelonucleosides followed by 0[Pg.13]

Like sodium hydroxide and sodium methoxide, sodium methyl mercaptide merely detosylates an isolated secondary sulfonyloxy group, as in methyl 6-deoxy-3,4-0-isopropylidene-2-0-tosyl-a-D-galactoside226 and methyl 4,6-O-benzylidene-3-0-methyl-2-0-tosyl-a-D-galactoside.162... 

A key compound for levoglucosan chemistry is 1,6-anhydro-2,4-di-<3-tosyl-/ -D-gl ucopyranose (36)176 which, after treatment with sodium ethoxide, affords a valuable starting compound, l,6 3,4-dianhydro-2-O-tosyl-jS-D-galactopyranose, as a single product (see Section IV. 1). Another example illustrating synthetic versatility of the ditosylate 36 is its oxidation to 3-keto derivative 37124.210.211 followed by reductive detosylation to afford the useful chiral synthon, l,6-anhydro-2,4-dideoxy-/i-D-g/ycero-hcxopyranos-3-ulose (38).210,212 Keto derivative 37 is readily isomerized by the action of pyridine into compounds of the D-arabino, D-xylo, and D-lyxo configurations.210... 

A cyclization reaction involving the sulfonamide 267 finalized an efficient synthetic approach to the COX-inhihitor 268 after subsequent simultaneous ester hydrolysis and detosylation (Equation 82) <2003JOC4104>. Indoles have also been prepared by reaction of (2-aminobenzyl)triphenylphosphonium salts with carboxylic acid anhydrides in the presence of a base <2002TL2885>. Exposure of o-(benzoylamino)benzonitriles to a-bromoketones under basic conditions gives 3-aminoindole derivatives <2001BML2169>. 

Scheme 18 shows Heathcock s total synthesis of ( )-discorhabdin E by the same procedure as discorhabdin C [74]. The reaction of the imine 62, derived from 61, and o-bromotyramine furnished 63. The treatment of 63 with three equivalents of CUCI2 and four equivalents of EtsN under bubbling O2 gave the W-tosyldiscorhabdin E 64, the detosylation of which with NaOMe resulted in the formation of ( )-discorhabdin E. 

Alkaline saponification of polymer-bound sugar ester did not proceed very smoothly, but when polymer-sulfonate sugar esters were employed, the cleavage involving detosylation and O-alkyl fission of the sulfonate ester (KOAc-DMF) proceeded smoothly (Guthrie et at., 1973), producing 0-acetates. From this it may be concluded that the OAc group is not affected under these conditions. 

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