Di-tert-butyl peroxide (DTBP)
Di-tert-butyl peroxide is a very stable organic peroxide, that is often used a radical initiator, as it performs homolysis at temperatures above 100°C.
Recent Literature
An esterification of primary benzylic C-H bonds with carboxylic acids using di-tert-butyl
peroxide as an oxidant is catalyzed by novel ionic iron(III) complexes
containing an imidazolinium cation. The reaction offers a broad generality and
tolerates sterically hindered starting materials.
B. Lu, F. Zhu, H.-M. Sun, Q. Shen, Org. Lett.,
2017, 19, 1132-1135.
In the presence of a catalytic amount of copper(II) acetate and di-tert-butyl
peroxide, a cross-coupling reaction of anilines with alkylborane reagents gives
N-alkylated anilines in good to excellent yields. Phenols are also
applicable for this reaction.
S. Sueki, Y. Kuninobu, Org. Lett., 2013,
15, 1544-1547.
The key to the success of a general catalytic procedure for the cross-coupling
of primary amides and alkylboronic acids was the identification of a mild base
(NaOSiMe3) and oxidant (di-tert-butyl peroxide) to promote the
copper-catalyzed reaction in high yield. This transformation provides a facile,
high-yielding method for the monoalkylation of amides.
S. A. Rossi, K. W. Shimkin, Q. Xu, L. M. Mori-Quiroz, D. A. Watson, Org. Lett., 2013,
15, 2314-2317.
An efficient copper-catalyzed amidation of benzylic hydrocarbons and inactive
aliphatic alkanes with simple amides proceeded smoothly without any ligand. A
wide range of N-alkylated aromatic and aliphatic amides, sulfonamides,
and imides were synthesized in good yields.
H.-T. Zeng, J.-M. Huang, Org. Lett.,
2015,
17, 4276-4279.
An earth-abundant iron catalyst enables a dehydrogenative acylation of enamides
with aldehydes to provide valuable β-ketoenamides with excellent functional group tolerance.
The C-H acylation occurs with absolute Z-selectivity.
R.-H. Liu, Z.-Y. Shen, C. Wang, T.-P. Loh, X.-H. Hu,
Org. Lett., 2020, 22, 944-949.
A convenient Fe-catalyzed A-D-A-T-type radical-dual-difunctionalization and
cross-coupling of two different alkenes provides chain elongated and
trifluoromethylated aromatic alkenes.
J. Zhao, R.-X. Liu, C.-P. Luo, L. Yang,
Org. Lett., 2020, 22, 6776-6779.
A convenient method for the synthesis of aryl thioamides from aryl aldehydes and
tetramethylthiuram disulfide (TMTD) in the presence of CuI and di-tert-butyl
peroxide (DTBP) avoids the use of a sulfurating reagent. The protocol offers
broad substrate scope, very good yields, operability and uses commercially
available and inexpensive raw materials.
M.-T. Zeng, M. Wang, H.-Y. Peng, Y. Cheng, Z.-B. Dong, Synthesis, 2018, 50,
644-650.
Regiospecific radical reactions of β-alkyl nitroalkenes with sulfonyl hydrazides
provide allyl sulfones with high regioselectivity in the presence of
dimethylformamide (DMF), whereas reactions in acetonitrile provide vinyl
sulfones.
Y. Wang, G. Xiong, C. Zhang, Y. Chen, J. Org. Chem., 2021, 86,
4018-4026.
The use of DTBP as radical initiator and a copper salt as promoter enables
the preparation of allylic alcohol, benzyl, and alkane derivatives via a radical
mechanism. The C(sp3)-H bond in various alcohols, toluene derivatives,
and alkanes were successfully alkenylated with β-nitrostyrenes to yield the
desired products in good yields.
S.-r. Guo, Y.-q. Yuan,
Synlett, 2015, 26, 1961-1968.
An efficient method enables the synthesis of α-cyanomethyl-β-dicarbonyls in good
yields from MeCN and simple 1,3-dicarbonyls. A radical mechanism is proposed.
C. Wang, Y. Li, M. Gong, Q. Wu, J. Zhang, J. K. Kim, M. Huang, Y. Wu, Org. Lett.,
2016, 18, 4151-4153.
An efficient coupling of arylboronic acids with dimethyldisulfide under
metal-free conditions provides aryl methyl sulfides. The method offers
operational simplicity, satisfactory yields, excellent functional-group
tolerance, as well as mild reaction conditions.
X.-m. Wu, J.-m. Lou, G.-b. Yan,
Synlett, 2016, 27, 2269-2273.
The use of inorganic sodium metabisulfite as the sulfur dioxide surrogate and
di-tert-butyl peroxide as source of the methyl radical enables a direct
C-H methylsulfonylation of alkenes. This method provides convenient access to (E)-2-methyl
styrenyl sulfones in good yields.
F.-S. He, Y. Gong, P. Rojsitthisak, J. Wu, J. Org. Chem., 2019, 84,
13159-13163.
An iron-catalyzed α-C(sp3)-H activation of cyclic and acyclic ethers provides
an efficient and green method for the synthesis of mixed acetals in very good
yields. The robustness of this protocol is demonstrated by the late-stage
oxidation of a structurally complex natural product.
W. Han, L. Cheng, H. Zhao, Synlett, 2020,
31,
1400-1403.
A regioselective oxidative allylic C(sp3)-H arylation of readily
available unactivated terminal and internal olefins with a broad range of
heteroaryl boronic acids is catalyzed by cheap, abundant, and nontoxic Cu2O.
This method does not require traditional coupling partners with preinstalled
leaving groups at the allylic position, thus offering an alternative
method to allylic arylation.
S. Pal, M. Cotard, B. Gérardin, C. Hoarau, C. Schneider, Org. Lett., 2021, 23,
3130-3135.
Copper(I) salts catalyze a synthesis of multisubstituted furans from readily
available acetophenones and electron-deficient alkynes via direct C(sp3)-H
bond functionalization under radical reaction conditions in the presence of di-tert-butyl
peroxide as an external oxidant. This method offers an efficient access to
biologically important scaffolds from simple compounds.
S. Manna, A. P. Antonchick, Org. Lett.,
2015,
17, 4300-4303.
A radical-promoted cross-dehydrogenative coupling strategy enables a metal- and
base-free one-pot synthesis of 2,5-diaryl 1,3,4-oxadiazoles via N-acylation
of aryl tetrazoles with aryl aldehydes, followed by thermal rearrangement. A
broad range of aryl tetrazoles and aryl aldehydes deliver the corresponding
products in good yields.
L. Wang, J. Cao, Q. Chen, M. He, J. Org. Chem.,
2015,
80, 4743-4748.
Cascade reactions of saturated cyclic amines with 2-oxo-2-arylacetic acids
enable a highly regioselective and versatile synthesis of acylated N-heterocycles.
In this cascade process, the copper catalyst is believed to play a crucial role
not only in dehydrogenation but also in the decarboxylation and cross coupling
reaction.
X. Shi, X. Chen, M. Wang, X. Zhang, X. Fan, J. Org. Chem., 2018, 83,
6524-6533.
A copper-catalyzed sp3 C-H functionalization of 2-alkyl-N-substituted
benzamides provides an efficient approach to various functionalized
isoindolinones without preparation of halogenated substitutes, use of expensive
transition metals, or toxic Sn or CO gas.
K. Nozawa-Kumada, J. Kadokawa, T. Kameyama, Y. Kondo, Org. Lett.,
2015,
17, 4479-4481.
A transition-metal-free, iodine-mediated oxidative intramolecular amination of
anilines provides indolines via cleavage of unactivated (sp3)C-H
and N-H bonds. The reaction could be performed on a gram scale for the synthesis
of functionalized indolines.
J. Long, X. Cao, L. Zhu, R. Qiu, C.-T. Au, S.-F. Yin, T. Iwasaki, N. Kambe, Org. Lett.,
2017, 19, 2793-2796.
Iodine-catalyzed cascade reactions of substituted thiophenols with alkynes under
metal- and solvent-free conditions enable the synthesis of benzothiophene
derivatives in good yields. Such an efficient, economical, and green
transformation should provide an attractive approach to various benzothiophenes.
K. Yan, S. Yang, M. Zhang, W. Wei, Y. Liu, L. Tian, H. Wang,
Synlett, 2015, 26, 1890-1894.
Copper-catalyzed C-H bond activation enables a facile, efficient, and simple
protocol for direct oxidative C-H amination of benzoxazoles with primary amines
using tert-butyl peroxide (TBP) as oxidant under air. Various substituted
aminobenzoxazoles were synthesized with very good yields.
J. Gu, C. Cai,
Synlett, 2015, 26, 639-642.
Triggered by alkyl radicals, varieties of 2-isocyanoaryl thioethers
containing aliphatic, aryl, and heteroaromatic groups can be cleaved and
precisely reinstalled to give benzothiazole derivatives. Mechanistic studies reveal that
the cascade reaction undertakes an intermolecular pathway.
K. Luo, W.-C. Yang, K. Wei, Y. Liu, J.-K. Wang, L. Wu,
Org. Lett., 2019, 21, 7851-7856.
A copper/iodine cocatalyzed decarboxylative cyclization of α-amino acids with
either 2-benzoylpyridines or 2-benzoylquinolines provides 1,3-disubstituted
imidazo[1,5-a]pyridines and 1,3-disubstituted imidazo[1,5-a]quinolines
in excellent yields.
H. Wang, W. Xu, L. Xin, W. Liu, Z. Wang, K. Xu, J. Org. Chem.,
2016,
81, 3681-3687.
Pharmaceutically important azolo[1,5-a]pyrimidines can be synthesized
from widely available 3- or 5-aminoazoles, aldehydes, and triethylamine. The key
is the in situ generation of an acyclic enamine followed by an annulation
reaction. This strategy is capable of constructing a range of 5,6-unsubstituted
pyrazolo[1,5-a]pyrimidines and [1,2,4]triazolo[1,5-a]pyrimidines.
Q. Gao, Z. Sun, Q. Xia, R. Li, W. Wang, S. Ma, Y. Chai, M. Wu, W. Hu, P.
Ábrányi-Baloghm G. M. Keserű, X. Han, Org. Lett., 2021, 23,
2621-2625.
An iron(III)-catalyzed oxidative coupling of alcohols/methyl arenes with
2-amino phenyl ketones provides a broad range of 4-quinolones. Alcohols and methyl arenes are
oxidized to the aldehyde in the presence of an iron catalyst and di-tert-butyl
peroxide, followed by condensation with amine/Mannich-type
cyclization/oxidation.
S. B. Lee, Y. Jang, J. Ahn, S. Chun, D.-C. Oh, S. Hong,
Org. Lett., 2020, 22, 8382-8386.
A simple switch in reaction conditions enables facile and efficient syntheses
of various valuable 3-aryl- and 3-aroylcoumarins by direct arylation and
aroylation of coumarins with glyoxals in a metal-free manner. This approach
accommodates a broad substrate scope and high yields of the two types of
cross-coupling reactions starting from identical starting materials.
A. Moazzam, M. Khodadadi, F. Jafarpour, M. Ghandi, J. Org. Chem., 2022, 87,
3630-3637.
A copper-catalyzed direct amination of cyclic amides in DMF forms aromatic
heterocyclic amines with readily available reagents via a radical mechanism. The
coordinating effect of the N1 atom provides assistance to the copper ions
for the activation and amination of C-O bonds.
P. Chen, K. Luo, X. Yu, X. Yuan, X. Liu, J. Lin, Y. Jin,
Org. Lett., 2020, 22, 6547-6551.
