SYNTHESIS hypervalent iodine compound

Varvoglis A (2003) Preparation of Hypervalent Iodine Compounds. 224 69-98 Verkade JG (2003) P(RNCH2CH2)3N Very Strong Non-ionic Bases Useful in Organic Synthesis. 223 1-44... 

All synthetically useful methods for the preparation of a multitude of hypervalent iodine compounds are discussed, with an emphasis on those methods developed over the last decade. In addition, special approaches of mechanistic interest and others suitable for the synthesis of individual compounds of interest are also briefly mentioned. 

Disulfides, diselenides, and ditellurides can be oxidized by hypervalent iodine compounds quite easily. Depending on the reaction conditions disulfides can be oxidized to sulfinic esters [59] or thiosulfonic S-esters [60,61]. Diselenides can be transformed into selenosulfonates [62]. Arenetellurinic mixed anhydrides are mild oxidants and can be obtained by oxidation of the corresponding ditellurides as shown in Scheme 9 [63]. Recently it was shown that a thioacetal based linker for solid-phase synthesis can be cleaved oxidatively using [bis(trifluoro-acetoxy)iodo]benzene 4 [64]. 

Using other hypervalent iodine compounds or different reagent combinations, various functional groups can be introduced in the a-position of ketones. a-Tosylations of ketones can be achieved directly using [hydroxy(tosyloxy)-iodo]benzene 6. The major drawback is the low regioselectivity observed in these reactions, although the a-tosylation of silyl enol ethers circumvents this problem. In the last few years some efforts have been done in the synthesis of chiral hypervalent iodine compounds [48, 53-55,113-117], but only a few of them have been used successfully in stereoselective synthesis. With chiral derivatives of type 59 it is possible to a-tosylate propiophenone with about 40% ee [56,118,119]. 

Analogously, after enolization with Ihmds, hypervalent iodine compounds such as PhI(OAc)2 have been used for the stereoselective synthesis of 2,3-disubstituted succinates by using the chiral oxazolidinone auxiliary (45 )-4-(phenylmethyl)-2-oxazolidinone (equation 19) . 

Kim, D.Y, Mang, J.Y, and Oh, D.Y, Reaction of silyl enol ethers with phosphite using hypervalent iodine compound. A new synthesis of 2-aryl-2-oxoalkylphosphonates, Synth. Commun., 24, 629, 1994. Hohnquist, C.R., and Roskamp, E.J., Tin(II) chloride catalyzed addition of diazo sulfones, diazo phosphine oxides, and diazo phosphonates to aldehydes. Tetrahedron Lett., 33, 1131, 1992. 

Tsarevsky has found that hypervalent iodine compounds can be used for the direct azidation of polystyrene and consecutive click-type functionalization [49]. In particular, polystyrene can be directly azidated in 1,2-dichloroethane or chlorobenzene using a combination of trimethylsilyl azide and (diacetoxyiodo)benzene. 2D NMR HMBC spectra indicate that the azido groups are attached to the polymer backbone and also possibly to the aryl pendant groups. Approximately one in every 11 styrene units can be modified by using a ratio of PhI(OAc)2 to trimethylsilyl azide to styrene units of 1 2.1 1 at 0 °C for 4 h followed by heating to 50 °C for 2 h in chlorobenzene. The azidated polymers have been further used as backbone precursors in the synthesis of polymeric brushes with hydrophilic side chains via a copper-catalyzed click reaction with poly(ethylene oxide) monomethyl ether 4-pentynoate [49],... 

Since the beginning of the twenty-first century, the organic chemistry of hypervalent iodine compounds has experienced an unprecedented, explosive development. Hypervalent iodine reagents are now commonly used in organic synthesis as efficient multipurpose reagents whose chemical properties are similar to derivatives of mercury, thallium, lead, osmium, chromium and other metals, but without the toxicity and environmental problems of these heavy metal congeners. One of the most impressive recent achievements in the field of iodine chemistry has been the discovery of hypervalent iodine catalysis. 

Diaryliodonium salts and other hypervalent iodine compounds in the synthesis of biaryls... 

Despite the demonstrated success of NBS and the hypervalent iodine compounds as modem HR reagents, the classical variant lead tetraacetate continues to find synthetic applications. A synthesis of the carbocyclic nucleoside (-)-aristeromycin features the conversion of amide 122 to Boc-protected amine 123. Similar tactics are used for syntheses of 6 - 3-... 

Asymmetric Synthesis with Hypervalent Iodine Compounds. 244... 

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