Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• applications of these compounds in photomedicine [23][25][26][27]. Recently we reported a porphyrin-photocatalyzed protocol for the arylation of enol acetates and elucidated the mechanism explaining why the electron-deficient porphyrin TPFPP is more efficient than TPP in the whole process (Scheme 4A). Briefly

• for the alkylation of aldehydes with diazo acetates in the presence of TPP. Arylation of heteroarenes with aryldiazonium salts using TPFPP as photocatalyst, and corresponding mechanism. A) Scope with different aryldiazonium salts and enol acetates. B) Photocatalytic cycles and comparison between TPP

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

• reported a selective photoredox merger C(sp3)–H alkylation/arylation of ethers using benzaldehyde as the photoorganocatalyst and nickel as the transition metal catalyst [57]. For the coupling between (3-bromopropyl)benzene (132) and THF (131), presented in Scheme 28, NiBr2·glyme (134) was employed as the

• good yields of 145h–l (Scheme 32). Additionally, products derived from ureas (i.e., 146), N,N-dimethylaniline (i.e., 147), amides (i.e., 148), and lactams (i.e., 149a) were obtained. Moreover, for N-methylpyrrolidinone, α-arylation was achieved in a good yield and regioselectivity for the substitution

• the aldehyde 161 could afford the acyl radical 168 through a HAT process, which then could add to diethyl maleate (154) and afford the desired product 162 through a propagation mechanism. In 2019, König and co-workers presented a catalytic arylation of aromatic aldehydes 170 by aryl bromides 171 using

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• (alkenyl)iodonium salts, which are air- and moisture-stable, nontoxic and easy to prepare compounds, have become efficient reagents for mild and selective arylation and alkenylation reactions in organic synthesis [16][17][18]. In particular, the use of these hypervalent iodine reagents in copper catalysis

• Feringa recently reported a catalytic method for the synthesis of mixed alkyl aryl phosphonates based on a copper-catalyzed arylation of phosphonates with diaryliodonium salts [32]. Encouraged by this work, in the context of an electrophilic alkenylation of phosphonates, we reasoned that the action of a

• , Table 1). We first run the reaction under the conditions reported for the copper-catalyzed O-arylation of phosphonates (CuCl as catalyst, 2,6-di-tert-butylpyridine (dtbpy) as additive in dichloromethane at 40 °C) [32]. Under those conditions, enol phosphonate 3a was the only product of the reaction

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• extensively developed to tune the optoelectronic properties [21]. Therefore, the development of more efficient and shorter step synthetic methods for the BODIPY derivatives, such as direct C–H functionalizations (e.g., arylation [22][23][24][25][26][27][28], annulation [29], olefination [30], styrylation [31

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• alkyl and alkoxy substituents at the 3, 6, 13, and 16-positions was achieved based on the ruthenium-catalyzed coupling reactions of anthraquinone derivatives with arylboronates via C–H and C–O bond cleavage. The reaction sequence involving the arylation, carbonyl methylenation, and oxidative cyclization

• effectively provided various tetrabenzo[a,d,j,m]coronenes in short steps from readily available starting materials. Tetrabenzo[a,d,j,m]coronenes possessing two different types of substituents were obtained selectively by sequential chemoselective C–O arylation and C–H arylation. The 1H NMR spectra of the

• tetrabenzo[a,d,j,m]coronene product indicated its self-assembling behavior in CDCl3. Keywords: C–H arylation; C–O arylation; oxidative cyclization; polycyclic aromatic hydrocarbons; ruthenium catalyst; Introduction Polycyclic aromatic hydrocarbons (PAHs) and their derivatives have attracted much attention

Copper-catalyzed remote C–H arylation of polycyclic aromatic hydrocarbons (PAHs)

• Anping Luo,
• Min Zhang,
• Zhangyi Fu,
• Jingbo Lan,
• Di Wu and
• Jingsong You

Beilstein J. Org. Chem. 2020, 16, 530–536, doi:10.3762/bjoc.16.49

• Anping Luo Min Zhang Zhangyi Fu Jingbo Lan Di Wu Jingsong You Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, P.R. China 10.3762/bjoc.16.49 Abstract The regioselective C–H arylation of

• substituted polycyclic aromatic hydrocarbons (PAHs) is a desired but challenging task. A copper-catalyzed C7–H arylation of 1-naphthamides has been developed by using aryliodonium salts as arylating reagents. This protocol does not need to use precious metal catalysts and tolerates wide variety of functional

• groups. Under standard conditions, the remote C–H arylation of other PAHs including phenanthrene-9-carboxamide, pyrene-1-carboxamide and fluoranthene-3-carboxamide has also accomplished, which provides an opportunity for the development of diverse organic optoelectronic materials. Keywords: C–H

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• excellent yields. Finally, a Meerwein arylation reaction was developed through the copper photocatalyzed formation of an aryl radical according to a reductive process. A large panel of aryl iodides was added to various pyrroles and electron-rich aromatic derivatives. The arylated products were obtained in

• aryl radical on ynamides or cyanamides, followed by a final cyclization. Using similar reaction conditions as those used for the Meerwein arylation, the three alkaloids were synthesized in good to excellent yield in a straightforward manner. In 2017, Fu, Peters, and co-workers reported the copper

• )(xantphos)]PF6. Chlorosulfonylation of styrene and alkyne derivatives by ATRA reactions. Reduction of aryl and alkyl halides with the complex [Cu(I)(bcp)(DPEPhos)]PF6. aIrradiation was carried out at 420 nm. All redox potential are reported vs SCE. Meerwein arylation of electron-rich aromatic derivatives

Room-temperature Pd/Ag direct arylation enabled by a radical pathway

• Amy L. Mayhugh and
• Christine K. Luscombe

Beilstein J. Org. Chem. 2020, 16, 384–390, doi:10.3762/bjoc.16.36

• Amy L. Mayhugh Christine K. Luscombe Department of Chemistry, University of Washington, Seattle, WA 98195, USA Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195, USA 10.3762/bjoc.16.36 Abstract Direct arylation is an appealing method for preparing π

• -conjugated materials, avoiding the prefunctionalization required for traditional cross-coupling methods. A major effort in organic electronic materials development is improving the environmental and economic impact of production; direct arylation polymerization (DArP) is an effective method to achieve these

• goals. Room-temperature polymerization would further improve the cost and energy efficiencies required to prepare these materials. Reported herein is new mechanistic work studying the underlying mechanism of room temperature direct arylation between iodobenzene and indole. Results indicate that room

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• through the arylation of 1 utilizing Ph2IOTf as arylating reagent [43][44]. Some copper-mediated arylation protocols using bromobenzene or iodobenzene [45][46] were also applicable to the preparation of 5, but significant loss of optical purity was inevitable. After the Pd-catalyzed cyclization under the

• the solid state [50][51][52][53][54]. Conclusion In summary, we have achieved the synthesis of a series of CPL-active polyheteroaromatic compounds from readily available chiral BINOLs via the O-arylation and subsequent palladium-catalyzed C–H/C–H coupling reaction. The substitution pattern on the

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• shown in Figure 12. Likewise, no result was obtained in the absence of light and photocatalyst. Aryl C–H arylation With the idea of introducing dual photoredox catalysis, in 2011, Sanford’s group reported the preparation of arylated compounds [115], important structural components of many natural

• previously reported methods required high temperatures [118][119][120]. A library of compounds was reported by that group using this approach, and a plausible mechanism is shown in Figure 13. Arylation of purines: Purine bases and purine nucleosides, which are common structural motifs in DNA and RNA, have an

• enormous range of applications in biology [121][122][123]. Inspired by other C–H arylation methods for N-heterocycles [124][125][126], recently, Guo and co-workers reported a dual photoredox-catalyzed C–H arylation of 6-arylpurine using photoredox catalyst 12a in the presence of a Pd cocatalyst [127]. With

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

• , there are few reports. For example, the supported Ru-catalysed regiospecific C(sp2)–H arylation of benzo[h]quinolines and the addition of vinylsilanes to the C–H bonds of α-tetralones were reported by Inoue and co-workers [41][42]. Pieters et al. reported the Ru nanoparticle-catalysed C–H deuteration

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• substrates, a mixture of regioisomers, resulting from α- and β-arylation, was formed (see Supporting Information File 1, Figures S16 and S17, S32 and S33) [21]. In case of the reaction with allyl alcohol, the generated products isomerized in situ to give the saturated aldehydes, compounds 12, 21, and 22, a

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• intermediate 118 takes place to obtained the final compound with regeneration of chiral catalyst 114. At almost the same time, Jorgensen et al. demonstrated that the intermolecular α-arylation of aldehydes via anodic oxidation could be performed using chiral secondary amine catalyst [76]. Constant current

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• -carboxylates bearing aryl moieties at the C-5 or C-4 position were appropriate starting substrates to construct TT scaffolds according to our strategy. Compounds 2a–k can be prepared either through direct palladium-catalyzed arylation of methyl 3-chlorothiophene-2-carboxylate [19] or through replacement of the

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• . The MS analysis revealed the formation of the N-arylated pyrazoles 33a and 33b as the main products (Scheme 1b). Both decomposition studies let us conclude, that intermolecular N-arylation is the major decomposition pathway of (pseudo)cyclic N-heterocycle-stabilized mesityl(phenyl)-λ3-iodanes

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• at either α or β-position has been of particular interest [23]. Just to mention Córdova’s α-oxygenation [11][12][13] or β-alkylation or β-arylation reported by Melchiorre [16] and MacMillan [17][18]) which represents only a tip of an iceberg of photochemical methods for the introduction of

Regioselective Pd-catalyzed direct C1- and C2-arylations of lilolidine for the access to 5,6-dihydropyrrolo[3,2,1-ij]quinoline derivatives

• Hai-Yun Huang,
• Haoran Li,
• Thierry Roisnel,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2019, 15, 2069–2075, doi:10.3762/bjoc.15.204

• acetate bases in DMA was found to promote the regioselective arylation at α-position of the nitrogen atom of lilolidine with a wide variety of aryl bromides. From these α-arylated lilolidines, a second arylation at the β-position gives the access to α,β-diarylated lilolidines containing two different aryl

• aryl groups at α- and β-positions via two-fold Pd-catalyzed C–H bond functionalizations, iii) on the synthesis of 5,6-dihydrodibenzo[a,c]pyrido[3,2,1-jk]carbazoles via three successive C–H bond functionalization steps (Scheme 1c). Results and Discussion Based on our previous results on the arylation of

• marketed drugs contain these units. Therefore, the reactivity of 3- and 4-bromo-substituted pyridines, 3-bromoquinoline and 4-bromoisoquinoline for the α-arylation of lilolidine was also studied. In all cases, the desired N-containing coupling products 16–19 were obtained in high regioselectivities and in

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• Ar(aryl)–Se bonds [9][10][11][12][13]. Various metals, such as Pd, Ni, Fe, and Cu have been used to catalyze the reactions of a Se source with aryl donors. Among these, Cu-catalyzed tandem cyclization via a one-step Ullmann-type Se-arylation and Csp2–H selenation are efficient methods for

• could be easily prepared according to a previously reported general method [17]. The N-arylation of benzo[d]imidazoles with 1-bromo-2-fluorobenzene derivatives in the presence of K3PO4 (5 equiv) at 150 °C gave 1a–i in 45–99% yields. All synthetic details including the preparation method for 1-(2

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• for the generation of carbon radicals via single-electron transfer (SET). In 2016, Barriault and co-workers reported a methodology that features the utilization of dimeric gold complex [Au2(dppm)2]Cl2 and ultraviolet A (UV, 365 nm) light to direct arylation of bromide-substituted butenolides or cyclic

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• structurally related since they contain an (R)-1-aryl-2-propanamine moiety. The synthesis of the respective intermediates (R)-16 and (R)-17 commenced from the ester (2R,1'R)-5f and relied on arylation of Weinreb amide (2R,1'R)-18 to afford the aziridine ketone 19. Its highly stereoselective reduction with the

• aziridine ring opening combined with functionalization of the C2 substituent and optional alkylation or arylation of the nitrogen atom [44]. Following a similar regioselective aziridine opening, a mixture of epimeric amino alcohols (2R/S,1'R)-23 was prepared in two steps from the aziridine alcohol (2R/S,1'R

• -hydroxypropyl fragment which could also be derived from the aziridine amide (2R,1'S)-8 (Scheme 28) [19]. N-Boc-protected amine (2S,1'S)-108 was converted to a key 1,3-oxazolidin-2-one (5S,1'S)-109 by trifluoroborate-catalyzed regioselective and stereospecific (SN2 displacement) cyclization. N-Arylation and

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

• ][42][43][44]. Various copper salts have been used as Lewis acid in homogeneous catalysis. CuO nanoparticles (NPs) were used for C–N, C–S, C–O cross-coupling reactions and C-arylation. Recently, exploiting the cross-coupling tendency of CuO NPs, Reddy et al. have reported their use as a heterogeneous

• , recyclable catalyst in the N-arylation of indoles [45][46]. Copper catalysts have shown exceptional enantioselectivity for reactions such as hydrosilylation, hydroboration, and heterogeneous as well as homogeneous hydrogenation [47][48][49]. Also, the copper salts found used as oxidants in a number of

• easy recovery and reusability [69]. The role of rhodium in synthetic chemistry Rhodium in the form of Wilkinsons catalyst [RhCl(PPh3)3] played a major role in the field of catalysis [70]. Rhodium is capable of catalyzing a number of organic reactions viz., heterocyclic alkylation and arylation with a

Synthesis of 9-O-arylated berberines via copper-catalyzed C_Ar–O coupling reactions

• Qiaoqiao Teng,
• Xinhui Zhu,
• Qianqian Guo,
• Weihua Jiang,
• Jiang Liu and
• Qi Meng

Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161

• 9-O-phenylene-bridged berberine dimer (5) was synthesized by copper-catalyzed cross-coupling of tetrahydroberberrubine and aryl iodides, followed by oxidation with I2. Keywords: arylation; berberines; cross-coupling; copper; lipophilicity; structural modification; Introduction Berberine (BBR) is a

• high lipophilicity, however, they have been rarely used to functionalize BBR. To the best of our knowledge, only three groups have reported the coupling of aryl groups to the C8 [5][16] and the C12 position [17] of BBR, while 9-O-arylation has not been reported thus far. This is quite surprising given

Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups

• Sean H. Kennedy,
• Makafui Gasonoo and
• Douglas A. Klumpp

Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153

• in the Brønsted superacid CF3SO3H, the substrate undergoes two types of reactions. In the presence of only the superacid, the highly ionized intermediate(s) provide a double cyclization product having two pyrido[1,2-a]indole rings. With added benzene, an arylation product is obtained. A mechanism is

• ), compound 9 undergoes two types of reactions. When the substrate is ionized in the presence of benzene and CF3SO3H, the arylation product 10 is formed as the major product (Scheme 3). Presumably, compound 10 is formed as a mixture of meso and dl stereoisomers. Similar reaction products were observed in our

• providing pentacation 13 then the hexacation 14. The product forming steps occur through either 13 or 14. For the arylation product 10, charge delocalization at the carbocation leads to nucleophilic attack at the para-position of the phenyl group. This SEAr step is followed by protonation at the methine

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• reaction) for selected transformations (1a→13→16→17 for mechanism A, 1a→13→22→23 for mechanism B) was explored. Formation of complex 13 from allene 1a and AlCl3 is exergonic (−26.7 kcal/mol) and thermodynamically favorable. The arylation stage for mechanism A (16→17) is significantly less endergonic (22.6

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• -cyclopropylation reactions, a transformation which is similar to the Chan [45], Evans [46], Lam [47] arylation reaction of N–H and O–H containing substrates. These seminal reports greatly contributed to the synthesis of cyclopropylated compounds in addition to expanding the scope of copper-catalyzed reactions in