Categories: Synthesis of N-Heterocycles > benzo-fused N-Heterocycles >
Synthesis of isatins
Recent Literature
An I2/TBHP-mediated oxidation of commercially available indoles
affords isatins in moderate to good yields.
Y. Zi, Z.-J. Cai, S.-Y. Wang, S.-J. Ji, Org. Lett., 2014,
16, 3094-3097.
The reagent mixture NaI/IBX-SO3K, containing a sulfonylated
derivative of 2-iodoxybenzoic acid, was employed for an oxidative direct
conversion of indoles into isatins. A synthetic route toward IBX-SO3K
and the X-ray crystal structure of the reagent are presented.
A. Bredenkamp, F. Mohr, S. F. Kirsch,
Synthesis, 2015, 47, 1937-1943.
A convenient oxidation of oxindoles with molecular oxygen in the presence of
tert-butyl nitrite as an additive enables a mild and metal-free synthesis of
isatins without the need for any catalyst or base.
W.-T. Wei, W.-W. Ying, W.-M. Zhu, Y. Wu, Y.-L. Huang, Y.-Q. Cao, Y.-N. Wang, H.
Liang,
Synlett, 2017, 28, 2307-2310.
Recombination of alkyl radicals derived from indolin-2-ones with the tert-butylhydroperoxy
radical affords 3-(tert-butylperoxy)indolin-2-one intermediates that can
be further transformed into indoline-2,3-diones under air. This strategy
provides a simple, effcient, and metal-free route to indolinediones.
W.-W. Ying, W.-M. Zhu, H. Liang, W.-T. Wei,
Synlett, 2018, 29, 215-218.
The use of a catalytic amount I2 and TBHP as stoichiometric oxidant
enables a simple and atom economic one-pot synthesis of isatins from 2′-aminoacetophenones
via oxidative amido cyclization of the sp3 C-H bond. In the presence
of a stoichiometric amount of iodine, the reaction yields iodoisatines. The
reaction proceeds through sequential iodination, Kornblum oxidation, and
amidation in one pot.
A. Ilangovan, G. Satish, J. Org. Chem., 2014,
79, 4984-4991.
Cross-dehydrogenative C-N annulations and dealkylative C-N annulations of 2′-N-aryl/alkylaminoacetophenones
and 2′-N,N-dialkylaminoacetophenones respectively in the presence of
Cu(OAc)2·H2O, NaOAc and air gave isatins in good yields.
However, on reaction with CuBr, 2′-N-benzylaminoacetophenones underwent
selective oxidation at the benzylic position to provide the corresponding
benzamides exclusively.
A. Ilanovan, G. Satish, Org. Lett., 2013,
15, 5726-5729.
An electrochemical oxygenation of indoles provides isatins by merging with a
complementary cathode oxygen reduction reaction. This green protocol uses
molecular oxygen as the sole oxidant, is free of an an electron transfer
mediator, and enables gram-scale preparation.
W. Zhuang, J. Zhang, C. Ma, J. S. Wright, X. Zhang, S.-F. Ni, Q. Huang, Org. Lett.,
2022, 24, 4229-4233.
A simple electrochemical oxidation of 2'-aminoacetophenones in the presence of
n-Bu4NI provides various isatins with moderate to good yields
via C(sp3)-H oxidation followed by intramolecular
C-N bond formation. A radical-based pathway is proposed.
P. Qian, J.-H. Su, Y. Wang, M. Bi, Z. Zha, Z. Wang, J. Org. Chem.,
2017, 82, 6434-6440.
Molecular iodine promoted an efficient synthesis of isatins from 2′-aminophenylacetylenes,
2′-aminostyrenes, and 2′-amino-β-ketoesters via oxidative amidation. The
reaction involves iodination, followed by Kornblum oxidation, and intramolecular
amidation in one pot.
G. Satish, A. Polu, T. Ramar, A. Ilangovan, J. Org. Chem.,
2015,
80, 5167-5175.
An efficient and environmentally friendly conversion of α-hydroxy N-arylamides
into isatins in very good yields proceeded smoothly under metal-free conditions
in the presence of hydrogen peroxide as oxidant. This convenient method offers
broad substrate scope.
J. Li, X. Cheng, X. Ma, G. Lv, Z. Zhan, M. Guan, Y. Wu,
Synlett, 2016, 27, 2485-2488.
Isatins can be synthesized from α-formyl amides in good yields via one-pot
intramolecular cyclization-oxidation reaction in the presence of pyridinium
chlorochromate (PCC). The reaction proceeded smoothly under air, offers a broad
substrate scope, and is operationally simple.
Q. Yue, Y. Wang, L. Hai, L. Guo, H. Yin, Y. Wu,
Synlett, 2016, 27, 1292-1296.