An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones

• Gernot A. Eller,
• Gytė Vilkauskaitė,
• Algirdas Šačkus,
• Vytas Martynaitis,
• Ashenafi Damtew Mamuye,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2018, 14, 1287–1292, doi:10.3762/bjoc.14.110

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• application due to their reduced toxicity, ready availability and lower costs as replacement for transition metals leading to several “metal-free” like chemical transformations. The ongoing demand of modern synthetic chemistry for the development of catalytic enantioselective C–C bond formation reactions

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• benzotropylium ion 45. Secondly, 11 is obtained in 18% yield after benzylic bromination of 42 with NBS, followed by in situ elimination reaction of the labile bromide 43 mediated by t-BuOK (Scheme 9). Palladium-catalyzed C–C bond-formation reactions such as Heck and Sonogashira couplings are employed in a wide

Hypervalent iodine-guided electrophilic substitution: para-selective substitution across aryl iodonium compounds with benzyl groups

• Cyrus Mowdawalla,
• Faiz Ahmed,
• Tian Li,
• Kiet Pham,
• Loma Dave,
• Grace Kim and
• I. F. Dempsey Hyatt

Beilstein J. Org. Chem. 2018, 14, 1039–1045, doi:10.3762/bjoc.14.91

• that many of these useful reagents became a staple in synthetic chemistry laboratories [1][2]. Although hypervalent iodine reagents are commonly used in oxidation reactions, they have also found their own niche in useful C–C bond-formation and C–H activation reactions [3][4][5]. One such C–C bond

• same reaction conditions as the RICR. The resulting diphenylmethane structure obtained after the C–C bond formation could have relevant medicinal applications since it is the core of many marketed pharmaceutical drugs with antihistaminic and anxiolytic properties [23][24][25][26]. Results and

• weaker electron-donating and electron-withdrawing groups are used (Table 2, entries 1, 2, 4, 5 and 6), the C–C bond formation occurs para to the iodine, but when strong electron-donating groups are used (Table 2, entries 7 and 8) then the para-selectivity is dictated by that group. The effect of electron

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• of a pre-synthesized (hetero)aryl with a ribosyl moiety (Figure 5A) [48][49][62]. The C–C bond formation usually involves a functional group at C1' of the ribosyl moiety that is amenable to additional functionalization (Figure 5B). Like other nucleoside coupling approaches (other than the well-known

• bond formation is an important goal, but often difficult to attain [62]. Among the aforementioned approaches for C-nucleoside syntheses, the coupling of (hetero)aryls to the ribosyl moiety has seen the widest application [52][53][58][62][63][64][65][69][70][71][72][73][74][75][76][77]. This can be

• Vorbrüggen coupling reaction [66], the synthesis of C-nucleosides typically gives a mixture of stereoisomers (α and β) at the anomeric carbon [48][49][54][62][67][68]. Since the naturally occurring nucleosides (and most biologically active nucleosides) are β-anomers, achieving 100% stereospecificity in C–C

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• alkenylation reaction of pivalophenone N–H imine with an alkenyl phosphate. The reaction tolerates various substituted pivalophenone N–H imines as well as cyclic and acyclic alkenyl phosphates. Keywords: alkenylation; C–C bond formation; C–H activation; cobalt; imine; Introduction Transition-metal-catalyzed

• obtained in an E-rich form from an E/Z mixture (1:1) of the starting alkenyl phosphate, demonstrating the E/Z isomerization during the C–C-bond formation. The E/Z isomerization was also observed for the conversion of cyclododecenyl phosphate (E/Z = 9:1) to the product 3af (E/Z = 3:1). Expectedly, 4

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• the presence of excess amounts of oxidant. On the other hand, the toxicity of residual traces of transition metal (photo)catalyst in products is also highly concerned. Consequently, metal-free and environmentally friendly oxidative C–C bond formation is highly desired. Electrochemistry has proved to

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• in this process was essential for the effective C−C bond formation. They proposed the catalytic cycle depicted in Scheme 20 which begins with the reaction between chiral ligand 51, ZnEt2 and ethyl bromoacetate (9b) to give complex G. Addition of the aldehyde to the latter results in the formation of

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• bond formation (path A), as postulated by Griesbeck et al. for the photocyclization of phthaloyl-L-methionine [58]. Alternatively, the alcoholate obtained after C–C bond formation may cyclize to the oxazolidine (path B), as known from reactions of 1a with organometallic reagents [48][49][50]. When

• and protonation furnishes the observed benzylated hydroxyphthalimidine derivatives 3a–q. The nucleophilic cyclization to the oxazolidine derivative 4 may occur at different stages of the photodecarboxylation (Scheme 8). The phthalimide radical anion may undergo nucleophilic cyclization prior to C–C

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• ]. This sequence provides ready access to these compounds. Next, 2-(3,3-difluoroallyl)biphenyl (5a), without an aryl group at its vinylic position, was subjected to the conditions examined in entries 1–3 of Table 1. In contrast to 1a, iodoarylation of 5a proceeded through C–C-bond formation exclusively at

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• NMR spectroscopic monitoring and revealed that the diastereoselectivity was determined during C–C bond formation step. A diastereoselective streptopyrrolidine analogue, containing three contiguous stereogenic centers, was smoothly obtained as a sole diastereomer in 70% yield. Structure of an azlactone

• bond formation, such as a dimerization process. We herein report a diastereoselective dimerization of azlactones using potassium or sodium trichloroacetate salts and acetonitrile as solvent. Besides, a reaction mechanism is proposed based on NMR studies and the relative stereochemistry of the major

• . Although no trichloromethylation product was observed, we found out that by switching the solvent, the isolated major product comes from dimerization of azlactones. At this point, we turned our attention towards this product, envisioning the development of an atom-economic reaction for stereoselective C–C

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• bond isostere [6]. Using this strategy, a mutant tripeptide containing two different peptide bond isosteres could be synthesized (Figure 3). In 2016, Konno and co-workers developed a stereoselective chromium-mediated C–F bond cleavage followed by a C–C bond formation to access (Z)-monofluoroalkenes

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• dimer 12, followed by the C–C bond formation involving the C(2) centers of the selenophene rings to yield the obtained twelve-membered heterocycle 9. In extension of the study, calculations were performed on the related symmetrical thiobenzophenone S-methanide by the same computational approach (see

• of thiobenzophenone S-methanide 1 (Ar1 = Ar2 = Ph). On the other hand, in the hetaryl functionalized thiocarbonyl S-methanide 8 the lowest activation energy was found for the C–C bond formation between C(2) atoms of the selenophen-2-yl ring, leading to the twelve-membered macrocyclic product 9

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• products 7e–i [41][44] in 60–70% yields (Table 5, entries 1–4). Conclusion In summary, we have developed a mild and direct process for the C–C bond formation from the reaction of the MBH alcohols 1a and 1b with β-dicarbonyl compounds 2 in the presence of a palladium catalyst and Et3B (promoter) with the

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• synthesized in 2011 by the Horne group [170], using a TPAP-catalyzed type B oxidative cyclization to form the densely substituted THF diol motif following a protocol of our group [25] (Scheme 22). The 5,6-dihydroxyalkene 101 was obtained from D-mannitol diacetonide via oxidation and C-C-bond formation. The

Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation

• Kirsty L. Wilson,
• Alan R. Kennedy,
• Jane Murray,
• Ben Greatrex,
• Craig Jamieson and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2016, 12, 2005–2011, doi:10.3762/bjoc.12.187

• , Dorset, SP8 4XT, UK School of Science and Technology, University of New England, Armidale, Australia, 2351 10.3762/bjoc.12.187 Abstract Pd-catalysed C–C bond formation is an essential tool within the pharmaceutical and agrochemical industries. Many of these reactions rely heavily on polar aprotic

• tool for C–C bond formation in the pharmaceutical industry [4]. While the Sonogashira reaction can be effectively carried out in a variety of media [1][2], in the general sense this process clearly relies upon the use of dipolar aprotic solvents, in particular DMF. Indeed, some 41% of all Sonogashira

• fundamental reactions that typically employ DMF [31][32]. The replacement of solvents with regulatory issues with bio-derived alternatives has provided a series of advances within the cross-coupling arena [33], allowing efficient C–C bond formation via cornerstone Pd-based methods including Suzuki–Miyaura [34

Artificial Diels–Alderase based on the transmembrane protein FhuA

• Hassan Osseili,
• Daniel F. Sauer,
• Klaus Beckerle,
• Marcus Arlt,
• Tomoki Himiyama,
• Tino Polen,
• Akira Onoda,
• Ulrich Schwaneberg,
• Takashi Hayashi and
• Jun Okuda

Beilstein J. Org. Chem. 2016, 12, 1314–1321, doi:10.3762/bjoc.12.124

• reported. The Diels–Alder reaction is a powerful C–C bond formation reaction, widely used in organic chemistry, e.g., for the synthesis of natural products [28]. This reaction is known to be catalyzed by Lewis acids such as a Cu(II) complex [29]. Additionally, structurally defined catalysts are found to

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• proposed on the basis of DFT calculations by Solé and Fernández [24][25][26]. The intermediate arylpalladium species is certainly generated by the standard oxidative insertion of palladium(0) into the C–I bond of the aryl iodide moiety. After the C–C bond formation leading to the bi- or tricyclic products

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

• the reaction, the iminium ions rapidly interconvert via single-bond rotation. After irreversible C–C bond formation the E-s-cis- and E-s-trans-iminiums give rise to the Z- and E-enamines, respectively, which undergo a directed enantiospecific protonation to give either the R- or S-product. Thus, the

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• of 10% of catalyst loading. Interestingly, the protocol employed gem-diols as equivalents of fluorinated aryl/alkyl methyl ketone enolates for the C–C bond formation accompanied the release of trifluoroacetate. This method showed a broad substrate scope including gem-diols with phenyl rings

Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes

• H. Surya Prakash Rao and
• A. Veera Bhadra Rao

Beilstein J. Org. Chem. 2016, 12, 496–504, doi:10.3762/bjoc.12.49

• . Recently, we reported a copper-catalyzed C–C bond formation by substitution of the labile C(4)SMe group in 4H-chromenes or C(3)–OH in isoindolinones with aryl/alkenyl groups by employing the corresponding boronic acids [51][52]. Continuing these efforts, we designed a copper-catalyzed synthesis of a

• PhCu(OTf) (15) and B(OH)2(OTf) [61]. The intermediate 15 then reacts with diphenylmethanol 9 to provide the intermediate 16. Formation of the intermediate 16 can be attributed to Lewis acidic characteristics of 15 and Lewis basic characteristics of diphenylmethanol (9a). The crucial C–C bond formation

• provide triarylmethanes. However, when we employed 2,6-dimethoxyphenylboronic acid 10l, surprisingly, we isolated the triarylmethane 11l, in which the C–C bond formation took place on the C(3) carbon of the 2,6-dimethoxyphenylboronic acid instead of the C(1) carbon, as illustrated in 11m (Scheme 4

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

• -substituted heterocycles has been considered as an efficient organic synthetic strategy, which is often featured by a new ring and dual C–C bond formation in one process [35][36][37][38][39][40][41][42]. Recently, the group of Liu reported a cascade alkylarylation of N-alkyl-N-phenylacryamide with simple

N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions

• Senem Akkoç,
• Yetkin Gök,
• İlhan Özer İlhan and
• Veysel Kayser

Beilstein J. Org. Chem. 2016, 12, 81–88, doi:10.3762/bjoc.12.9

• arylation (for 5–8) reactions. As catalysts, they demonstrated a highly efficient route for the formation of asymmetric biaryl compounds even though they were used in very low loading. For example, all compounds displayed good catalytic activity for the C–C bond formation of 4-tert-butylphenylboronic acid

• used as a substrate with catalyst 6, sp2–sp2 C–C bond formation with 2-n-butylfuran was achieved with a yield of 49% in just 1 h (Table 1, entry 5). The product was obtained in a much lower yield when the same reaction was carried out with 5 as a catalyst. Compounds 7 and 8 as catalysts were displaying

• better results than complexes 5 and 6 for the same reaction (Table 1, entries 6 and 7). When we employed electron-neutral bromobenzene as a substrate instead of 4-bromoacetophenone, C–C bond formation (2-butyl-5-phenylthiophene) was achieved in 97% yield using catalyst 8 at 110 °C with a reaction time of

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• different products: the SN2-product or the SN2’-product (Scheme 24). Usually, SN2’ regioselective allylic substitutions, which create a new stereogenic center, are more valuable. Methods that allow the SN2’ regioselective C–C bond formation have been extensively studied over the past years. In contrast to

Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

• Hang Ren,
• Haoyun An,
• Paul J. Hatala,
• William C. Stevens Jr,
• Jingchao Tao and
• Baicheng He

Beilstein J. Org. Chem. 2015, 11, 2509–2520, doi:10.3762/bjoc.11.272

• ’-deoxy-3’-fluororibosides 16–20. Synthesis of 2-aminopurine 3’-deoxy-3’-fluororibosides 21–23. C–C bond formation by Stille and Suzuki cross-coupling. Antitumor activity of newly synthesized compounds. Supporting Information Supporting Information File 444: Experimental procedures, characterization data