Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• , and TBHP acting as both an oxidant and a radical initiator. In 2015, Wang et al. reported the synthesis of quinoline lactones by the double oxidative dehydrogenation (DOD) reaction between glycine derivatives and tetrahydrofuran using the FeCl2/HCl/TBHP system (Scheme 19) [80]. This practical coupling

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• afforded the products in excellent yields. The authors also conducted various experimental and theoretical studies to analyze the reaction mechanism. The proposed mechanism begins with the oxidative dehydrogenation of the alcohol to afford the aldehyde which undergoes condensation with ammonia to give the

• corresponding imine. Finally, oxidative dehydrogenation results in the formation of the nitrile. Conclusion This review summarizes the recent progress in ruthenium-catalyzed cyanation reactions. Due to the wide application of nitrile compounds in pharmaceutical and biological fields, cyanation reactions have

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• accelerating imine formation (I-19), and under the catalysis of a chiral phosphoric acid, intramolecular nucleophilic addition occurs to form I-20, followed by oxidative dehydrogenation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). In the presence of 10 mol % chiral phosphoric acid CPA 7, the axially

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• benzylideneacetone in acetonitrile in the presence of p-TsOH and DDQ resulted in polyfunctionalized carbazoles in satisfactory yields. The reaction mechanism included the DDQ oxidative dehydrogenation of 3-(indol-3-yl)-1,3-diphenylpropan-1-ones to the corresponding 3-vinylindoles, their acid-catalyzed Diels–Alder

• chemical structures of the carbazoles were fully characterized by 1H NMR, 13C NMR, IR, and HRMS spectra. To explain the formation of the products, a plausible reaction mechanism was proposed in Scheme 2 on the basis of the previously reported reaction [48][53]. Firstly, the DDQ oxidative dehydrogenation of

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• oxidative dehydrogenation [19]. Recently, Maji and co-workers reported the synthesis of 3-alkenylindoles from indoles and α-hydrogen-containing alkyl-/arylaldehydes by successive Brønsted acid/base catalysis (Scheme 1) [20]. The third category, which is also the most explored and popular one, involves the

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

• Qiao Li,
• Chen Zhuang,
• Donghua Wang,
• Wei Zhang,
• Rongxuan Jia,
• Fengxia Sun,
• Yilin Zhang and
• Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

• catalytic amount of azobis(isobutyronitrile) (AIBN) in CCl4 (Scheme 1c) [61][62]. In 2002, Nicolaou and co-workers found that ortho-iodoxybenzoic acid (IBX) could also effectively dehydrogenate chromanones to chromones (Scheme 1d, method 1) [63]. Moreover, active MnO2 was also found useful in the oxidative

• dehydrogenation of chromanones at a relatively high temperature of 110 °C (Scheme 1d, method 2) [64][65]. Although all of the above methods have their respective merits in the preparation of the corresponding chromone derivatives, it is obvious that some of them suffer from drawbacks, such as the requirement of a

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• , mild reaction conditions (room temperature) and excellent functional group tolerance. In this instance, the copper catalyst may only promote the generation of the tert-butoxyl radical from TBHP. The oxidation of the intermediate A with t-BuOOH produces a carbocation B, followed by an oxidative

• dehydrogenation process to afford the target product. Also in 2015, Li and co-workers [146] developed a mild and fast Cu(I/II)-catalyzed trifluoromethylation procedure to obtain 3-trifluoromethylcoumarins. The reaction was carried out with a CuCl/CF3SO2Na/TBHP system under continuous-flow conditions, affording

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• well, giving the corresponding products in excellent yields. This protocol served as a novel route for the synthesis of imidazo[1,5-a]pyridines 37 via oxidative amination of sp3 C–H bonds in the aerial atmosphere. The reaction involved oxidative dehydrogenation of benzylamine intermediate 92 to form 93

• which underwent resonance to give 94. This was followed by intramolecular amination, oxidative dehydrogenation, and rearrangement to yield the final product 37 (Scheme 31). A one-pot, tandem reaction promoted by a I2/CuO system to synthesize imidazo[1,2-a]pyridines was reported by Cai et al. (Scheme 32

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• presence of copper reagent. Then, the trifluoromethyl radical reacts with substrates affording intermediate A, which may be oxidized to a carbocation B, followed by an oxidative dehydrogenation process delivering the target product. Copper-mediated/catalyzed direct trifluoromethylation of C(sp)–H

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• /bjoc.13.162 Abstract Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective

• . This review discusses various oxidative dehydrogenation strategies of C–C and C–N bonds to generate nitrogen heteroarenes from their corresponding heterocyclic substrates. The strategies are categorized under stoichiometric and catalytic usage of reagents that facilitate such transformations. The

• application of these strategies in the synthesis of nitrogen heteroarene natural products and synthetic drug intermediates are also discussed. We hope this review will arouse sufficient interest among the scientific community to further advance the application of oxidative dehydrogenation in the synthesis of

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• situ by the oxidative dehydrogenation of aldoximes in the presence of various oxidants [26][27][28][29], or by the dehydrohalogenation of hydroxyiminoyl halides promoted by organic or inorganic bases [30][31][32]. A less used synthetic procedure involves the oxidative dehydration of primary nitro

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• oxidative dehydrogenation. Then we tested another procedure, in which the co-oxidant O2 was replaced with Oxone [29], but even in this case the conversion (6% by GC) was worse than that achieved using bubbling O2. Further attempts of optimizing the oxidative dehydrogenative step of the Stahl protocol were

Aryl nitrile oxide cycloaddition reactions in the presence of pinacol boronic acid ester

• Sarah L. Harding,
• Sebastian M. Marcuccio and
• G. Paul Savage

Beilstein J. Org. Chem. 2012, 8, 606–612, doi:10.3762/bjoc.8.67

• nitrile oxides involves the dehydration of primary nitro compounds [21]. Aryl nitrile oxides are more commonly prepared by chlorination of aldoximes followed by dehydrohalogenation of the resulting hydroximoyl chlorides, or by direct oxidative dehydrogenation of the aldoximes (Scheme 2) [17]. While the

• halogenation–dehydrohalogenation process is most common, several methods involving direct oxidative dehydrogenation of aldoximes have been reported, including the use of lead tetraacetate [22][23], mercury(II) acetate [24], hypervalent iodine [25][26], and manganese(IV) oxide [27]. We were interested in

Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine

• Jessica Baiget,
• Sabin Llona-Minguez,
• Stuart Lang,
• Simon P. MacKay,
• Colin J. Suckling and
• Oliver B. Sutcliffe

Beilstein J. Org. Chem. 2011, 7, 1407–1411, doi:10.3762/bjoc.7.164

• means of either a Pictet–Spengler or a Bischler–Napieralski cyclization followed by an oxidative dehydrogenation process [13][14][15]. Inspired by nature’s example, we wished to design a synthetic route to the β-carboline scaffold, which was biomimetic and could be carried out in a single operation. One