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.
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 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.
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.
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.