Silver trifluoroacetate, reaction with iodine

Vicinal iodo carboxylates may also be prepared from the reaction of olefins either with iodine and potassium iodate in acetic acid/ or with N-iodosuccinimide and a carboxylic acid in chloroform. " A number of new procedures for effecting the hydroxylation or acyloxylation of olefins in a manner similar to the Prevost or Woodward-Prevost reactions include the following iodo acetoxylation with iodine and potassium chlorate in acetic acid followed by acetolysis with potassium acetate reaction with iV-bromoacetamide and silver acetate in acetic acid reaction with thallium(III) acetate in acetic acid and reaction with iodine tris(trifluoroacetate) in pentane. ... 

The addition of iodine trifluoroacetate (produced by reaction of iodine with silver trifluoroacetate) to unsaturated carbohydrates has been investigated.134 Treatment of 5,6-dideoxy-l,2-0-isopropylidene-a-D-xylo-hex-5-enofuranose (89) with silver trifluoroacetate and iodine in acetonitrile gave 3,6-anhydro-5-deoxy-5-iodo-l,2-0-iso-propylidene-a-D-gluco(and /3-L-ido)furanose (91) and 5-deoxy-5-iodo-l,2-0-isopropylidene-6-0-(trifluoroacetyl)-o -D-gluco(and/or /3-L-ido)-furanose (92), with the former preponderating. Component 91 was converted into 3,6-anhydro-5-deoxy-l,2-0-isopropylidene-a-D-xj/io-hexofuranose (94) by hydrogenation over Raney nickel (see also, Section III,3 p. 299), and component 92 was converted into 5-deoxy-l,2-0-isopropylidene-a-D-xy/o-hexofuranose (95) by treat-... 

Another strategy for the synthesis of 5-deoxyhexoses involves the anti-Markovnikov hydration of a 5,6-alkene derivative, as first developed by Wolfrom.97,100 Since that report, the same approach has been followed by several authors, and conditions for the key step have been improved. For example, starting from tosylate 43, treatment with sodium iodide resulted in the alkene 44. Addition of iodine trifluoracetate (produced in situ by the reaction of silver trifluoroacetate and iodine) to 44, followed by hydrogenation over... 

The Birckenbach-Goubeau-Waters reaction373-375 is another method of producing halogen cations acyl hypohalites are produced as intermediates in the reaction mixture by treating iodine (or bromine) with a molar equivalent amount of mercury acetate or silver acetate, trichloroacetate, perchlorate, sulfate, or trifluoroacetate (reactions b and c) ... 

Glacial acetic acid is a suitable solvent for use with silver acetate and CC14 or, up to 150°, nitrobenzene for use with silver trifluoroacetate. The Hunsdiecker reaction (see p. 1005) may intervene as competing reaction 377 trifluoroiodo-methane, for example, may be formed when iodine, silver trifluoroacetate, and nitrobenzene are heated in the absence of a substance that can be iodinated CF3COOAg + I2 ------------------------ CF3I + Agl + C02... 

Preparation by reaction of boron tribromide with 2,4-bis(benzyloxy)-5-iodoace-tophenone (SM) in methylene chloride with stirring for 5 min at -70° (97%). SM was obtained from 2,4-bis-(benzyloxy)acetophenone with iodine in the presence of silver trifluoroacetate in chloroform (89%) [2062]. 

While the silver and zinc salts were effective Lewis acids for these cyclizations, Kikugawa and coworkers reported that the alkoxynitrenium ions could be generated directly from hydroxamic esters (4) using hypervalent iodine oxidants such as hydroxy(tosyloxy) iodobenzene (HUB) and phenyliodine(lll)bis(trifluoroacetate) (PIFA) . Presumably, with such reagents the reactions proceed through A-(oxoiodobenzene) intermediates (54), which can themselves be regarded as anomeric hydroxamic esters and sources of alkoxynitrenium ions (55) (Scheme 11). 

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