When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• photocatalyst. The strategy was utilized for the C–H bond annulation of benzamides with alkynes, furnishing isoquinolones, an important moiety in various natural products (Figure 15) [78]. The C–H activation step was assisted by an 8-quinolyl DG and occurred under an oxygen atmosphere at room temperature. A

• variety of benzamides bearing different substituents at the ortho- and para-positions gave the products in good to excellent yields, while the meta-substituted substrates were converted into a mixture of two isomeric products. Moreover, amides containing heterocycles such as thienyl, pyrazolyl, pyridyl

• independently published alternative procedures based on the same dual catalytic system merging C–H activation and photoredox catalysis. In 2017, Xu’s group reported a variation of the ortho-arylation of acetanilides and benzamides with aryldiazonium salts [84], now compatible with a cheaper photosensitizer, i.e

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• Pd(OAc)2 (5 mol %), was involved in the design of an efficient annulation between benzamides and in situ-generated arynes. The process occurred under oxygen saturated atmosphere at room temperature, likewise offering a straightforward access to the phenanthridone backbone [93]. Conclusion

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• in a benzene solution by being irradiated for 16 h using a 100 W Hanovia medium-pressure mercury lamp. The aromatic aldehydes tested included benzaldehyde (8), 4-chlorobenzaldehyde, 2,4-dichlorobenzaldehyde, and 4-fluorobenzaldehyde, which gave the corresponding benzamides in moderate to low yield

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• , lithium diisopropylamide (LDA)-mediated cyclisation of 2-(methylthio)benzamides, which were obtained by directed ortho-metalation of the respective benzamides followed by quenching with dimethyl disulfide [27] (Supporting Information File 1, Scheme S1). In general, we found the LDA-mediated cyclisation

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

• reagent. Notably, Cu(II) salts were crucial for forming the aryl–CF3 bonds. In Yu’s study, benzamides and benzylamines were well trifluoromethylated via a Pd(II)/Pd(IV) catalytic cycle with the addition of TFA (and Ag2O) (Scheme 66a). With an acetamido group as a directing group, Shi developed an

Installation of -SO₂F groups onto primary amides

• Jing Liu,
• Shi-Meng Wang,
• Njud S. Alharbi and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 1907–1912, doi:10.3762/bjoc.15.186

• was worth noting that not only para- (1b–h) but also meta- (1j–l) and ortho- (1m–o) substituted benzamides afforded the desired products in generally good yields. Arylcarboxylic amides (1p and 1q) bearing bis-substitutions also behaved well under the standard conditions. Heterocyclic aromatic

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• parentheses. Control experiments for the oxidative cleavage of C–C bonds. Plausible reaction mechanism for the synthesis of N-alkylated benzamides 3. Optimization of reaction conditions.a Supporting Information Supporting Information File 174: Experimental procedures, characterization data and copies of 1H

Intramolecular cascade annulation triggered by rhodium(III)-catalyzed sequential C(sp²)–H activation and C(sp³)–H amination

• Liangliang Song,
• Guilong Tian,
• Johan Van der Eycken and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 571–576, doi:10.3762/bjoc.15.52

• -catalyzed intramolecular annulation of alkyne-tethered hydroxamic esters for the synthesis of isoquinolones and pyridines without using external oxidants (Scheme 1a) [22]. Recently, we reported an intramolecular annulation of benzamides to synthesize indolizinones through RhIII-catalyzed C(sp2)–H activation

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• has been reported. Fragment-based design In 2012 Klein et al. obtained the benzamides 46 and 47, as well as the hydroxamic acid 48 as hits within an SPR screening, which were further evaluated in ITC experiments in order to have a clearer view on the thermodynamic parameters (Figure 21). The

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• fact, the conversion of the tert-butyl derivative 3j at 120 °C was slow, affording the desired product 1 in low yield (<10%) after 60 min. In this case, harsher reaction conditions were required for complete consumption of the starting material. In turn, the less reactive benzamides 3c,d,k required

A challenging redox neutral Cp*Co(III)-catalysed alkylation of acetanilides with 3-buten-2-one: synthesis and key insights into the mechanism through DFT calculations

• Andrew Kenny,
• Alba Pisarello,
• Arron Bird,
• Paula G. Chirila,
• Alex Hamilton and
• Christopher J. Whiteoak

Beilstein J. Org. Chem. 2018, 14, 2366–2374, doi:10.3762/bjoc.14.212

• relative infancy and often transferability between substrate classes remains unresolved and limitations not fully understood. This study focuses on the translation of an established Cp*Co(III)-catalysed alkylation of benzamides to related acetanilides using 3-buten-2-one as coupling partner. The developed

• functionalisation of benzamides we wondered if the previously developed protocol could be directly transferred successfully to acetanilides, therefore further expanding the applicability of the developed methodology. The expected product from this reaction has previously been obtained through a C–H

• -neutral alternative, obviating the requirement for addition of terminal oxidant (Scheme 1c). Herein, our results from this study will be reported and the difficulties of this translation will be explained through a DFT study of the mechanism, which will also be directly compared with the use of benzamides

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• )-catalyzed hydroarylation of terminal alkynes with arenes. Co(III)-catalyzed hydroarylation of alkynes with amides. Co(III)-catalyzed C–H alkenylation of arenes. Co-catalyzed alkylation of substituted benzamides with alkenes. Co-catalyzed switchable hydroarylation of styrenes with 2-aryl pyridines. Co

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• 80 using Pd(II) 79 and PIDA (15) as the oxidative system in acetonitrile. Iodine(III)-catalyzed spiroaminocyclization of amides 76 to spirolactam 77 using bis(iodoarene) 81 as a precatalyst in the presence of PAA. Iodine(III)-catalyzed spirolactonization of N-phenyl benzamides 82 to spirolactams 83

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• evaluated their antiproliferative activity as well as their DNA binding affinity [98]. It has been confirmed that the most active conjugates are unsymmetrical triaryl benzamides 35 and 36 comprising of a bulky and alkylating chlorobenzylic substituent, respectively, and a polar amino side chain. Conjugate

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

• Romain Sallio,
• Stéphane Lebrun,
• Frédéric Capet,
• Francine Agbossou-Niedercorn,
• Christophe Michon and
• Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

• -substituted isoindolinones 1 and 2 could be obtained in high enantioselectivities from the intermediates (2R,3S)-3–5 after removal of the chiral auxiliary (Scheme 1). (2R,3S)-bicyclic lactams 3–5 could be prepared by the asymmetric intramolecular organo-catalyzed aza-Michael reaction of (R)-benzamides 6–8

• bearing an acrylamide group at the ortho-position of the benzene ring. Synthesis of parent chiral benzamides 6–8 The use of a stereoselective chiral auxiliary which could be incorporated and removed easily without racemization was crucial for the success of our strategy. These requirements prompted us to

• comparison to all the studied cinchoninium catalysts, the use of cinchonidinium catalyst 21 proved to be less efficient with a 48% de (Table 2, entry 17). With the optimized reaction conditions in hand, catalyst 18c was employed in the asymmetric intramolecular aza-Michael reaction of benzamides (R)-6a–d

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• generation of N-triflylbenzamides by direct reaction of various triflyl derivatives with benzamides or benzoic acids has been less systematically explored. Most compounds synthesized by these approaches are N-alkylated or N-arylated and have been formed unintentionally as byproducts [26][27][28][29][30][31

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

• functional group and copper(I). Benzamides were widely used building blocks in medicinal chemistry. In 2014, Dai and Yu [54] achieved an elegant copper-mediated ortho-selective trifluoromethylation of benzamides assisted by an N-phenyloxazoline group. But one major problem was the low selectivity, and that

• the ditrifluoromethylation product was formed as well. Recently, Tan and co-workers [55] designed a highly mono-selective ortho-trifluoromethylation of benzamides assisted with an 8-aminoquinoline directing group. This reaction employed simple copper salt CuBr as the promoter and Togni’s reagent II as

• a CF3 source (Scheme 34). Addition of water benefited the yield. A variety of functional groups such as methyl, ethyl, ester, fluoro, chloro, bromo, phenyl, methoxy, ethoxy as well as trifluoromethyl groups were well tolerated on the phenyl ring of benzamides and various ortho-trifluoromethylated

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• the metal catalyst from rhodium to iridium. In 2016, using an Ir(III) catalyst an unprecedented ortho-selective Csp2–H bond amidation of benzamides with sulfonyl azides as the amide source was done under solvent-free ball mill conditions (Scheme 51) [183]. They could also isolate cyclic iridium

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

• facilitate a variety of quinazolinones 44 (Scheme 12) [47]. N-Alkyl benzamides 44´ were also synthesized with this protocol. The average yield ranged from 30 to 92%. Other than methyl(hetero)arenes dimethylamides were also used as C-synthon for such intermolecular annulation to afford unsubstituted

Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides

• Ryota Miyaji,
• Yuuki Wada,
• Akira Matsumoto,
• Keisuke Asano and
• Seijiro Matsubara

Beilstein J. Org. Chem. 2017, 13, 1518–1523, doi:10.3762/bjoc.13.151

• functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatility of bifunctional organocatalysts for the enantioselective construction of axially chiral compounds

• chiral benzamides [36][37]. Results and Discussion We initiated our investigations using 3-hydroxy-N,N-diisopropylbenzamide (1a) and N-bromoacetamide (NBA, 4a) as a brominating reagent, with 10 mol % quinidine-derived bifunctional catalyst 3a, in toluene, at −40 °C. As expected, the tribrominated product

• enantioselectivities (Scheme 3); both 1k and 1l comprise a substituent ortho to the hydroxy group. These brominated axially chiral benzamides can further be derivatized for the synthesis of functional molecules [64]. To gain insight into the reaction mechanism, the reactions were performed using substrates 1m and 1n

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• propionamides 4a,b,h–k reacted readily under mild reaction conditions (Table 3, entries 1, 2, and 8–11), while for isobutyramide 4c a higher temperature was necessary (Table 3, entry 3). Finally, the more sterically hindered pivalamide 4d and the less reactive benzamides 4e–g required harsher reaction

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• facilitate C–H hydroxylation of benzoic acids and heteroarenes [55]. An amidation reaction between benzoic acid and 2-(pyridine-2-yl)isopropylamine gave N-(2-(pyridine-2-yl)isopropyl)benzamides, which could be hydroxylated at the ortho position in moderate to excellent yields. The reaction was promoted by a

• stoichiometric amount of Cu(OAc)2 in the presence of Ag2CO3 and TBAI as additives in DMF at 100 °C (Scheme 26). Notably, their protocol was so efficient that the reactions could accomplish within 1 hour. The substrate scope showed benzamides bearing both electron-donating groups and electron-withdrawing groups

• were converted to the corresponding phenols. Moreover, heteroarenes, such as pyridine and thiophenes, could also give hydroxylated products under their conditions. In 2016, Jana and co-workers used N-(8-quinolinyl)benzamides as starting materials, and ortho-hydroxylation occurred in the presence of a

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• to both of the carbonyl oxygens. During the course of studying the addition of aromatic thiols to α,β-unsaturated benzamides and enones, Chen, Ding, and Wu first reported the conjugate addition of thiophenol (23) to N-methacryloyl benzamide 91 followed by enantioselective protonation using Takemoto’s

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• examined, and a lower chemical yield was found when the reaction was performed at 100 °C (Table 1, entry 16). With the optimized conditions developed, we then carried out a substrate generality study using various types of N-(2-methylallyl)benzamides 4 to react with cyclohexane (2a). As shown in Scheme 2

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• related ring-fused products, the formation of other ring sized scaffolds such as five-membered structure were much less. An interesting cascade reaction between DG-functionalized benzamides 99 and malonates 100, which enabled the synthesis of indolinones 101 via selective C–C and C–N bond construction

• for lactam synthesis. Copper-catalyzed amidation/sulfonamidation of aryl C–H bonds. C–H amidation of pyridinylbenzenes and indoles. Mechanism of the Cu-catalyzed C2-amidation of indoles. Copper-catalyzed, 2-phenyl oxazole-assisted C–H amidation of benzamides. DG-assisted amidation/imidation of indole