Hydroxy iodobenzene

A similar approach was carried out reacting an enohzable ketone with amides in the presence of the hypervalent iodine(III) reagent (hydroxy(tosyl-oxy)iodobenzene, HDNIB) [48]. The reaction was carried out imder solvent-... 

RNH2 (R=alkyl, but not aryl) are phenyliodosyl bis(trifluoroacetate), Phl(0-C0CF3)2 and hydroxy(tosyloxy)iodobenzene, PhI(OH)OTs. A mixture of NBS, Hg(OAc)2, and R OH is one of several reagent mixtures that convert an amide (RCONH2) to the carbamate (RNHCOOR ) (R=primary, secondary, or tertiary... 

Hydroxy(tosyloxy)iodobenzene 2014 reacts with phenyltrimethylsilane 81 in boiling acetonitrile to give diphenyliodonium tosylate 2015 and trimethylsilanol 4 or HMDSO 7 [184, 185]. Likewise, treatment of 2,5-bis(trimethylsilyl)furan 2016 with 2014 in boiling acetonitrile/methanol affords 78% iodonium tosylate 2017 and trimethylsilanol 4 [185]. In the presence of Bp3-OEt2 iodosobenzene oxidizes allyl-trimethylsilanes such as 2018 to unsaturated aldehydes such as 2019 in 63% yield, with formation of iodobenzene and trimethylsilanol 4 [186]. Analogously, vinyltrimethylsilanes such as (Z)-l-trimethylsilyl-2-phenylethylene 2020 afford, via 2021, acetylenes such as phenylacetylene in 61% yield and iodobenzene and trimethylsilanol 4 [187] (Scheme 12.54). 

The a-halo ketone has also been prepared in situ (NBS, benzoyl peroxide, light) [89IJC(B)500]. Similarly, imidazo[2,l-b][l,3,4]thiadiazoles are accessible from 2-amino-l,3,4-thiadiazoles and acetophenones in the presence of hydroxy(tosyloxy)iodobenzene (HTIB). This latter method has been proposed as more convenient and versatile than the reaction of 2-amino-1,3,4-thiadizoles with a-halo ketones [94IJC(B)686, 94JCR(S)38, 94MI5],... 

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). 

Lin and Zhang reported the synthesis of l-hydroxy-3-methylcarbazole (23) starting from the nitro derivative 625 (578). This synthesis uses a Buchwald-Hartwig amination for the synthesis of the diphenylamine 628. After protection of the hydroxy group in the nitrophenol 625 as a benzyl ether, the nitro group was reduced to the corresponding amino derivative 627. Amination of 627 with iodobenzene under Buchwald-Hartwig conditions afforded the diarylamine 628. Palladium(ll)-mediated cyclization of 628 led to the carbazole derivative 629, albeit in low... 

A variant on the sequence in which the third aromatic ring is introduced by reaction of the ketone in chloroethyl ether (9-4) with the hthio reagent from 1-4-di-iodobenzene leads in several steps to iodoxifene (9-5) [10]. 4-Hydroxy-tamoxifen, in which a hydroxyl group has been introduced on one of the benzene rings, comprises one of the principal metabolites of the drug. The unnatural meta isomer of... 

A catalytic amount of acid is sufficient, on the other hand, for the halogenation of activated aromatics such as polyalkylbenzenes by all the three NXSs. NIS iodinates mesitylene in presence of the very mild acid hydroxy(tosyloxy)iodobenzene (Koser s reagent, HTIB)7 2. NBS performs much better in the presence of / -toluenesulfonic acid and NCS shows the highest yields when trifluoromethanesulfonic acid is used as catalyst743. This difference in reactivity leads to a novel method for preparation of a mixed halogenated mesitylene (equation 100). 

Hydroxy(tosyloxy)iodobenzene (HTIB 30) is another hypervalent organoiodine compound which acts as a Hofmann reagent, converting aliphatic carboxamides to alkylammonium tosylates in refluxing acetonitrile (equation 23). 

Vasudevan, A., Koser, G. F. Direct conversion of iong-chain carboxamides to aikyiammonium tosyiates with hydroxy(tosyioxy)iodobenzene, a notabie improvement over the ciassicai Hofmann reaction. J. Org. Chem. 1988, 53, 5158-5160. 

Ingenious application of remote oxidation has opened the way to a novel and potentially useful degradation of 5a-cholestan-3a-ol to 3a-hydroxy-5a-androstan-17-one ( androsterone ). The radical relay process, whereby photolysis of an iodoaryl ester with iodobenzene dichloride introduces a chlorine atom or unsaturation into the steroid nucleus, has been adapted by use of the 3a-(4 -iodobiphenyl-3-carboxylate) (301). The size of this ester grouping allows the iodine atom to come... 

Acetylamino)-5[[(2-(hydroxy-ethyDamino] carbonyl]-2,4,6-triiodobenzoic acid 3-Amino-alpha-ethyl-2,4,6-tri-iodobenzene-propanoic acid Alpha-Ethyl-3-hydroxy-2,4,6-triiodobenzene-propionic acid 3-(Acetylethylamino)-2,4,6-tri-iodobenzene-propionicacid 3 - [ [(Dimethylamino)-methylenel amino]-2,4,6-triiodobenzene-propanoic acid Sodium salt Calcium salt... 

Hydroxy (tosyloxy)iodobenzene [phenyl(hydroxyl)tosyloxy iodine, bydroxy(4-methyl-... 

However, by analogy with the reactions of alkenes, an alternative mechanism via the formation of a pentacoordinate cyclic periodinane (145) is also plausible. Oxidative addition of HTIB or its analogs to the enol affords the periodinane. Ligand coupling yields a new elusive intermediate, an a-hydroxy-iodinane (146), which undergoes elimination of iodobenzene. (Scheme 5.21)... 

The reaction of 1,3-dicarbonyl compounds with iodosylbenzene, hydroxy(tosyloxy)iodobenzene or hydroxy(mesyloxy)iodobenzene, gave similar results to those obtained with monocarbonyl compounds. However, only the 2-functionalised derivatives were obtained.234,249,266 Excellent results were observed in the case of substrates containing a perfluoroalkyl chain. Treatment of the fluoro dicarbonyl compounds (158) with HTIB afforded the a-tosyloxy compounds (159) which were isolated as their dihydrate. 

Hydroxy(tosyloxy)iodobenzene 3 a or hydroxy(methansulfonyl)iodobenzene 3 b and the corresponding ketone 4 were ground in an agate mortar for 10 min. The resulting mass formed a thin layer on the surface of the mortar. All this mass was moved to the center of the bottom of the mortar and the grinding was repeated for 10 min. The reaction mixture was dried under high vacuum and the residue washed with a small amount of diethyl ether. 

At a lower oxidation level, orffto-hydroxy-acyl-arenes undergo base-catalysed aldol condensations with aromatic aldehydes to give chalcones, °° which can be cyclised to 2,3-dihydro-chromones via an intramolecular Michael process the dihydro-chromones can in turn be dehydrogenated to produce chromones by a variety of methods, for example by bromination then dehydrobromination or by oxidation with the trityl cation, iodine, dimethyldioxirane or iodobenzene diacetate. ° ... 

Reactions can also be carried out in microemulsions. (Microemulsions have finer droplets of the oil phase than the usual emulsions.) They have been used in the hydroxy-carbonylation of iodobenzene (8.34).245... 

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