Hydroxy tosyloxy iodobenzene

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). 

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). 

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

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. 

Organohypervalent iodine(in) compounds are particularly usefiil as the oxidants in the Hofmann-type degradation of aliphatic or aromatic carboxamides to the respective amines [483]. The most common reagents for Hofmann-type rearrangements include (diacetoxyiodo)benzene [484-488], [bis(trifluoroacetoxy)-iodo]benzene [489-494], [hydroxy(tosyloxy)]iodobenzene [495-499] and their recyclable analogs (Chapter 5). The catalytic version of the Hofmann rearrangement using aryl iodides and m-chloroperoxybenzoic acid as terminal oxidant has also been reported (Section 4.1). 

Hydroxy(tosyloxy)iodobenzene [phenyl(hydroxyl)to yloxyiodine, hydroxy(4-methylbenzene ulfonato-O)phenyliodine, Koser s reagent] [27126-76-7] M 392.2, m 134-136°, 135-138 , 134-136 , 136-138.5 . 

Oxidation at the a position of a keto group is achieved with the hypervalent iodine compound hydroxy(tosyloxy)iodobenzene (HTIB). The reagent is insoluble in the medium, and the sonochemical effect corresponds to a mechanical activation, even if in this case a chemical role cannot be excluded. With unsymmetrical ketones, the reaction is practically non-selective (Eq. 68). 

R.D. Jadhav, H.D. Mistry, H. Motiwala, K.S. Kadam, S. Kandre, A. Gupte, A.K. Gangopadhyay, R. Sharma, A frcile one-pot synthesis of 3,5-disubstituted isoxazole derivatives using hydroxy (tosyloxy) iodobenzene, J. Heterocycl. Chem. 50 (2013) 774-780. 

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