Organic Chemistry Portal
Chemicals >> Oxidizing Agents > Hypervalent Iodine Compounds

Koser's Reagent
Hydroxy(tosyloxy)iodobenzene (HTIB)

HTIB is a commercially available reagent for the phenyliodination and oxytosylation of a range of organic substrates. For examples, ketones give α-tosyloxyketones, whereas alkenes form 1,2-ditosyloxyalkanes via syn addition.

A recently reported method enables a convenient access to Koser's Reagent and derivatives:

E. A. Merritt, V. M. T. Carneiro, L. F. Silva Jr., B. Olofsson, J. Org. Chem., 2010, 75, 7416-7419.54.

Recent Literature

Various α-tosyloxyketones were efficiently prepared in high yields from the reaction of ketones with m-chloroperbenzoic acid and p-toluenesulfonic acid in the presence of a catalytic amount of iodobenzene.
Y. Yamamoto, H. Togo, Synlett, 2006, 798-800.

Various ketones could be reacted into α-tosyloxy ketones in the presence of MCPBA, PTSA•H2O, catalytic amounts of iodine and tert-butylbenzene in a mixture of acetonitrile and 2,2,2-trifluoroethanol. In the reaction, 4-tert-butyl-1-iodobenzene is formed at first and then converted into the α-tosyloxylation reagent 4-tert-butyl-1-[(hydroxy)(tosyloxy)iodo]benzene by the reaction with MCPBA and PTSA•H2O.
A. Tanaka, K. Moriyama, H. Togo, Synlett, 2011, 1853-1854.

Enol esters were rapidly converted in high yields to their corresponding α-tosyloxy ketones in the presence of [hydroxy(tosyloxy)iodo]benzene (HTIB). Aromatic, aliphatic, and cyclic enol esters were found to be suitable substrates for the reaction.
B. Basdevant, C. Y. Legault, J. Org. Chem., 2015, 80, 6897-6902.

HTIB mediates an oxidative transposition of vinyl halides to provide α-halo ketones as useful and polyvalent synthetic precursors. Insights into the mechanism and an enantioselective transformation are reported too.
A. Jobin-Des Lauriers, C. Y. Legault, Org. Lett., 2016, 18, 108-111.

A combination of PhI(OAc)2 and BF3·Et2O promoted the Beckmann rearrangement of ketoximes to provide amides. The Beckmann rearrangement is preceded by acetylation of the hydroxy group of the ketoxime in situ, accelerating the Beckmann rearrangement. The reaction of ketoximes with Koser's reagent in the presence of THF provides ketones in high yields at room temperature.
T. Maegawa, R. Oishi, A. Maekawa, K. Segi, H. Hamamoto, A. Nakamura, Y. Miki, Synthesis, 2022, 54, 4095-4103.

A hypervalent iodine mediated α-alkylative umpolung reaction of carbonyl compounds with dialkylzinc as the alkyl source is applicable to a broad range of ketones including 1,3-dicarbonyl compounds and regular ketones via their lithium enolates. The α-alkylated carbonyl products are formed in very good yield. Meticulous analysis, NMR studies, trapping and crossover experiments, and computational studies suggest an ionic mechanism.
O. S. Shneider, E. Pisarevsky, P. Fristrup, A. M. Szpilman, Org. Lett., 2015, 17, 282-285.

Dehydrosulfurization using a hypervalent iodine(III) reagent enables a simple and efficient preparation of symmetrical and unsymmetrical carbodiimides from the corresponding thioureas. The oxidation afforded carbodiimides in excellent yields and high selectivity. A possible mechanism for the transformation is proposed.
C. Zhu, D. Xu, Y. Wei, Synthesis, 2011, 711-714.

Poly{[4-(hydroxy)(tosyloxy)iodo]styrene} was efficient in the halotosyloxylation reaction of alkynes with iodine or NBS or NCS. The polymer reagent could be regenerated and reused.
J.-M. Chen, X. Huang, Synthesis, 2004, 1557-1558.

The use of Koser's reagent enables an efficient synthesis of 3-tosyloxy-4-hydroxycoumarins under mild conditions. The reaction tolerates various functional groups.
B. Xu, Y. Gao, J. Han, Z. Xing, S. Zhao, Z. Zhang, R. Ren, L. Wang, J. Org. Chem., 2019, 84, 10136-10144.