1-Amido-3-(1H)-1,2-benziodoxoles: Stable amidoiodanes and reagents for direct amidation of organic substrates

Benziodoxole-based hypervalent iodine reagents for atom-transfer reactions

“…This method was further extended to the selective trifluoromethylation of cysteine in peptides using MeOH and water as solvent. 37 40 Trifluoromethylation of both secondary and primary 45 phosphines was also investigated (Table 3). 38 Both benziodoxolone 7 and benziodoxole 11a were efficient in this process, and 11a was more reactive.…”

“…In the case of highly unstable 40 structures or for the development of catalytic methods, less reactive reagents are desirable, however. Despite promising preliminary results mostly for heteroatom transfer, the number of benziodoxole-based reagents used in functionalization reactions other than simple oxidations constitutes only a 45 fraction of the reported structures and most of them are based on the  3 iodine benziodoxolone structure (Figure 1). Whereas the formation of C-C bond using non-cyclic iodonium reagents has been very successful in the last decades, 6c it is only in 2006 that Togni and co-workers reported the first use 50 of benziodoxole-derived reagents 7 and 11 for CF3 transfer.…”

“…Several other examples of tosyloxylation reactions using  3 or  5 -benziodoxole-based compounds were reported, but in these cases the active reagent was formed in situ. 18 45 Based on earlier results of Martin and Amey, 19 Braddock and co-workers improved the synthesis of bromo benziodoxole 9a. 20 They demonstrated that 9a was an efficient source of bromonium ion for the bromination of anisole (15) and the bromolactonization of 4-pentenoic acid (16) (eqn 2).…”

“…24c In this case, the reaction was discovered serendipitously when attempting the oxidation of alcohol 35. Hydroxylation happened immediately after oxidation of the 45 alcohol to the ketone.…”

“…40 In fact, the rare and limited examples of cyano or aryl transfer using benziodoxole-derived reagents stand in contrast with the impressive results obtained with non-cyclic iodonium salts. 6 However, this situation is completely different when we consider CF3-transfer reactions or direct alkynylations of 45 heterocycles: for both reactions, the use of benziodoxolederived reagents was essential for success. These two transformations will now be discussed in details.…”