Iodobenzene, diacetate, preparation

Quinoxalines 85 have been prepared by the reaction of diols with benzene-1,2-diamines in the presence of a ruthenium catalyst <06TL5633>. Iodobenzene diacetate has been suggested as a less toxic alternative to lead tetraacetate for the oxidative cyclisation of iminooximes to quinoxaline iV-oxides 86 <06TL4969>. 

The second most popular method of oxadiazole preparation starts from acylhydrazones 110, which undergo cyclization usually under the action of oxidizing agents (Br2, PhN02, HgO, iodobenzene diacetate). Also, the use of acetic anhydride can lead to cyclization of compound 110. The cyclization can be supported by microwave irradiation. In particular cases, heating is sufficient to accomplish the reaction. 

Several approaches to the 1,2,3-triazole core have been published in 2000. Iodobenzene diacetate-mediated oxidation of hydrazones 152 led to fused 1,2,3-triazoloheterocycles 153 <00SC417>. Treatment of oxazolone 154 with iso-pentyl nitrite in the presence of acetic acid gave 1,2,3-triazole 155, a precursor to 3-(W-l,2,3-triazolyl)-substituted a,P-unsaturated a amino acid derivatives <00SC2863>. Aroyl-substituted ketene aminals 156 reacted with aryl azides to provide polysubstituted 1,23-triazoles 157 <00HC387>. 2-Aryl-2T/,4/f-imidazo[43-d][l,2,3]triazoles 159 were prepared from the reaction of triethyl AM-ethyl-2-methyl-4-nitro-l//-imidazol-5-yl phosphoramidate (158) with aryl isocyanates <00TL9889>. 

Free or benzo-fused 1,2,3-triazoles 286 have been prepared by iodobenzene diacetate-mediated oxidation of hydrazones 285 (Equation 37) <2000SC417>. 

I, I-Bis(trif1uoroacetoxy)iodoDbenzene is prepared by dissolving, with heating, a given number of grams of (I,I-diacetoxyiodo)benzene (iodobenzene diacetate, Aldrich Chemical Company, Inc. see also Ovg. Synth., Collect. Vol. V, 1973, 660) in twice that number of milliliters of... 

Benzo[c]cinnolines have been conveniently prepared by the cyclization of symmetrically disubstituted 2,2-diami-nobiphenyls using iodobenzene diacetate as the oxidant <1996J(P1)83, CHEC-III(8.01.9.1)72>. A similar oxidation of 2,2,6-triamino-6-propylthiobiphenyl 49 afforded a new tetracyclic ring system 50 (Scheme 25) <2000JOC6388>. 

The third modification of the Hunsdiecker reaction is the so-called Sudrez modification,21 where the steroidal acids were treated with hypervalent iodine reagent in CCI4 to prepare steroidal chloride. The Sudrez modification also works for bromination using iodobenzene diacetate, bromine, and CH2Br2 as the solvent under irradiation as exemplified by transformations 14—>15.22 Unlike many variations described before, the Suarez modification tolerates a variety of functional groups. 

Preparation. The reagent can be prepared conveniently by dissolution of iodobenzene diacetate (formerly named iodosobenzene diacetate) in warm trifluoroacetic acid (53% yield). Other methods have been reported. 

In a complementary approach for preparing a-ketotriflates Varma and Kumar used the combination of iodobenzene diacetate and trifluoromethanesulfonic acid to prepare p-oxobis[trifluoromethanesulfonato(phenyl)iodme] 207 in situ. This reagent cleanly converted aromatic a-methyl ketones to the corresponding a-ketotriflates 204, which reacted with nitriles to afford 2-alkyl-5-aryloxazoles 206 in variable yield (Scheme 1.58). Mechanistically, the authors proposed the same... 

A convenient method for generating the alkoxy radical is by fragmentation of hypoiodites prepared in situ from the corresponding alcohol. This can be accomplished by treatment of the alcohol with iodine and lead tetraacetate or mercury(II) oxide, or with iodine with iodobenzene diacetate. For example, irradiation of the alcohol 29 under these latter conditions gave a high yield of the tetrahydrofuran 30 (4.29). In another apphcation of this chemistry, for the specific deprotection of benzyl ethers, irradiation of the alcohol 31 and A-iodosuccinimide (NIS) gave the cyclic acetal 32 (4.30). ... 

Lin and coworkers prepared 2-substituted quinazolines via a metal-free oxidative sp C—H/sp C—H cyclization of amidines (Scheme 23) (140L2822). Two methods were developed. Method A uses iodobenzene diacetate as a source of hypervalent iodine(lll) and a nonpolar solvent, toluene. In Method B potassium persulfate is used as the oxidant in the presence of a catalyst, TEMPO, and a polar solvent, acetonitrile. Both methods... 

Nitrile imines can also be prepared conveniently by the oxidation of easily accessible hydrazones (Scheme 5.45). The oxidant generally used is chloramine-T (N-chloro-N-sodio-p-toluenesulfonamide, CAT). Other oxidants such as iodobenzene diacetate (IBD) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone have also been used. 

The use of hypervalent iodine as an inexpensive alternative to transition metal catalysts was reported in 2013. The Liu group developed an efficient and mild iodine (III)-mediated one-pot synthesis of benzisoxazoles, which they then used for the preparation of isoxazolo[5,4-iodobenzene diacetate in a 1 2 mixture of water and acetonitrile at room temperature, followed by the addition of the aldehyde oxime and two more equivalents of iodobenzene diacetate. Upon observed completion, o-phenylenediamine was added to the reaction mixture which was subsequently heated at 50 °C for Sh.The respective phenazines were obtained in moderate yield. 

Willgerodt4 prepared iodosobenzene diacetate by adding chlorine to iodobenzene and hydrolyzing the dichloride to iodosobenzene, which was then reacted with acetic acid. Pausacker 6 used this method to synthesize a number of analogs but found it... 

Iodosobenzene diacetate is best prepared by the action of peracetic acid and acetic acid on iodobenzene. The present procedure is superior to earlier ones 5-8 because it uses inexpensive, commercially available peracetic acid, is faster, and gives higher yields. The procedure seems general for aiyl iodides with electron-releasing substituents, for the submitters have obtained good yields of diacetates from o-, m- and />-iodoto uene, 2- and 4-iodo-wt-xyiene, 2-iodo-/>-xylene, o-iodophenetole, and 4-iodobi-phenyl. 

A simple preparative method involves oxidation of iodobenzene with CrOj-AcjO-HjSO in acetic acid (79% yield). Other aryliodine(III) diacetates are accessible in the same manner. 

Preparation. The reagent is prepared by stirring iodosobenzene diacetate with iN sodium hydroxide, collecting and drying the solid, and macerating it with chloroform to remove a little iodobenzene. This procedure is preferable to an older one involving alkaline hydrolysis of iodosobenzene dichloride because iodoso-... 

Similarly, for an oxidant that contains an indirectly activated oxygen, the preparation method can always be used to determine the oxidant. For example, lodosylbenzene (PhlO), a common oxidant, is made by treatment of the hyperva-lent iodine reagent PhI(OAc)2 with sodium hydroxide. The diacetate is made from the action of peracetic acid and acetic acid on iodobenzene. Thus, the iodosylben-zene oxidant can be traced to hydrogen peroxide, which is used to make the peracetic acid. 

Preparative Methods diphenyliodonium triflate can be prepared by reaction of benzene with elemental iodine in tbe presence of potassium persulfate and trifluoroacetic acid in dicbloroetbane followed by ligand exchange with NaOTf in 71% yield. A one-pot reaction of iodobenzene and benzene with m-CPBA and trifluoromethanesulfonic acid at room temperature for 10 min also affords diphenyliodonium triflate in 92% yield. Diphenyliodonium triflate can be obtained in near-quantitative yield by reacting an excess of benzene (i.e., 4 equiv) with elemental iodine in the presence of m-CPBA and trifluoromethanesulfonic acid. More tedious and somewhat less efficient synthetic routes to diphenyliodonium triflate have been reported using iodosylbenzene (PhIO) or iodobenzene /J-diacetate (PhI(OAc)2), trifluoromethanesulfonic acid, and benzene as starting materials. Another preparation of diphenyliodonium triflate implies the reaction of phenylboronic acid with PhI(OAc)2 and trifluoromethanesulfonic acid in dichloromethane and proceeds in >90% yield. ... 

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