Reaction with triflic anhydride

On reaction with triflic anhydride, the mono oxides of 2,2 -bis(alkylthio)biphenyl are converted into a dithiadication (48) which spontaneously monodealkylates to give a thiasulfonium salt (49) <96TL667>. 

Coupling with enol esters (7, 93). A new synthesis of an alkyl-substituted alkene involves coupling of a lithium dialkyl cuprate with an enol triflate,1 available from a ketone by reaction with triflic anhydride and 2,6-di-t-butylpyridine.2 A wide variety of organocuprates can be used and the geometry of the enolate is largely retained. Reported yields are in the range 60 100%. 

Very simple and straightforward alkylation of NH-heterocycles (NaH, Cl(CH2) SMe, = 2 or 3, 68-86%) permits one-pot preparation of pyrrole and carbazole sulfide models for the reaction with triflic anhydride <2003S1191>. Cyclization of the (l/7-pyrrol-l-yl)alkyl sulfides 1470 obtained leads to 2,3-dihydropyrrolo[2,l- ][l,3]thiazole 1472 and 3,4-dihydro-2/7-pyrrolo[2,T ][l,3]thiazine 1473 via intermediate l-methyl-2,3-dihydropyrrolo[2,l-/ ][l,3]thiazol-1-ium or l-methyl-3,4-dihydro-27/-pyrrolo[2,T ][l,3]thiazin-Tium salts 1471 (n = Z or 3), respectively, that were isolated in high yields in most cases (Scheme 281) <2003S1191>. 

Related anchored l,l,3,3-tetraphenyl-2-oxa-l,3-diphospholanium bis-triflate (39) has been prepared by reaction of brominated poly(styrene-co-divinylbenzene) resin 38 with the phosphorous anion generated from l,2-bis(diphenylphosphino)ethane and sodium naphthalenide followed by further oxidation and reaction with triflic anhydride (Scheme 7.13) [55]. This supported reagent has also been employed, to a lesser extent than 37, for the formation of esters and amides by reaction of carboxylic acids with primary alcohols and amines, respectively. 

Carbohydrate triflates. Triflates of carbohydrates can be prepared in high yield by reaction with triflic anhydride. Thus the reaction of (1), l,2 5,6-di-O-isopropylidene-a-D-allofuranose, with triflic anhydride in pyridine at -15° gives the triflate (2) in 80% yield. When (1) is refluxed with triflic anhydride in... 

Nitriles. Aldoximes are dehydrated to nitriles by reaction with triflic anhydride and triethylamine in CH2CI2 at — 78 20° (equation I). ... 

Treatment of methyl 2-deoxy-3-D-e/> l /(ro-pentopyranoade with /-butyldiphenylsilyl chloride in the presence of silver nitrate followed by reaction with triflic anhydride gave methyl 3-d-Tbdms-2,4,5-trideoxy-a-D-g/ cero-pent-4-enopyranoside which on further reaction with /-butyllithium then tributyltin chloride affords stann ated glycal 17. In a similar way methyl 2-dtoxy-a-L-erythro-... 

Scheme 6.10 Synthesis of triflate-initiators from the corresponding alcohols by reaction with triflic anhydride in the presence of 2,6-di-tert-butyl pyridine as proton trap.

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