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.
Using a simple catalytic electrosynthetic protocol, an in situ generated
hypervalent iodine species eliminates chemical oxidants and the inevitable
chemical waste associated with their mode of action. The developed method has
been used for syntheses of dihydrooxazole and dihydro-1,3-oxazine derivatives,
and the α-tosyloxylation of ketones.
M. Elsherbini, W. J. Moran, J. Org. Chem., 2023, 88,
1424-1433.
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.
Convenient 1,3-dipolar cycloadditions between in situ generated nitrile oxides
from the corresponding aldoximes using [hydroxy(tosyloxy)iodo]benzene (HTIB,
Koser's reagent) and maleimides, styrene and acrylonitrile provide isoxazoline
derivatives. The described methodology is very attractive as it is operationally
simple, has broad scope, and does not require any base, metal, or other
additives.
R. Budhwan, M. Rawat, R. K. Peddinti, Synthesis, 2023,
55, 1904-1908.
Using a simple catalytic electrosynthetic protocol, an in situ generated
hypervalent iodine species eliminates chemical oxidants and the inevitable
chemical waste associated with their mode of action. The developed method has
been used for syntheses of dihydrooxazole and dihydro-1,3-oxazine derivatives,
and the α-tosyloxylation of ketones.
M. Elsherbini, W. J. Moran, J. Org. Chem., 2023, 88,
1424-1433.
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.
