Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• systems, while the observation of a higher enantioselectivity for the (Z)-isomer substrate 1a was characteristic for the phenol–NHC chiral ligand [4][6][8]. The result suggested that the chiral catalyst may mainly discriminate the hydrogen atom and the ethoxycarbonyl group at the α-position rather than

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• performed with remarkable stereoselectivity (97–99%). Furthermore, this catalytic system was easily upscalable (up to 10 g), and the chiral catalyst could be recycled without any loss of efficiency. Unfortunately, although a wide range of Grignard reagents led to excellent results, PhMgBr provided low

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

• stereoselective organic electrochemical reactions along with the synthetic accomplishments achieved with these methods. Keywords: chiral auxiliary; chiral catalyst; chiral electrode; chiral electrolyte; chiral mediator; electroorganic chemistry; Introduction Electric current-assisted exchange of electrons

• 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

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• nanoreactor because there is an acceleration of the dimerization by two orders of magnitude and the turnover of the catalyst was demonstrated. The synthesis of cyclic carbonates from epoxides and CO2 is an efficient method for CO2 fixation. The development of an effective chiral catalyst for the efficient

Dirhodium(II)-catalyzed [3 + 2] cycloaddition of N-arylaminocyclopropane with alkyne derivatives

• Wentong Liu,
• Yi Kuang,
• Zhifan Wang,
• Jin Zhu and
• Yuanhua Wang

Beilstein J. Org. Chem. 2019, 15, 542–550, doi:10.3762/bjoc.15.48

• a chiral catalyst, the obtained cycloaddition products are racemic. According to previous reports [16], after a series of arylcyclopropylamines 1 with different substituents were synthesized, the scope of 1 was then explored and the results are shown in Table 2. The data suggest that the electronic

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• understanding of the kinetics and mechanism of the individual reactions. In this paper we use density functional theory calculations to systematically study the different cofactor states in terms of energies and geometries. Benzoylformate decarboxylase (BFDC), which is a well characterized chiral catalyst

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• used as catalyst. This result could be ascribed to the effect of steric hindrance on the upper rim of calix[4]arene. So, the optimization and substrate scope studies were performed by using chiral catalyst 69f and up to 98% ee was obtained (Scheme 30). In order to confirm the role of the calixarene

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

• solvents. Further, they were able to improve the enantioselectivity by implying steric effects at the ortho/ortho′ (R = Et in 7) positions of the aromatics (Scheme 3) [33]. The regeneration of the catalyst was achieved by m-CPBA converting iodine compound 7′ to chiral catalyst 7. The authors predicted a

• catalyzed by a phase-transfer catalyst [74]. Their previous findings on the same reaction using a Cinchona-based phase-transfer catalyst [75] was further improved by using Maruoka’s binaphthyl-derived ammonium salt 110. The formation of intermediate 112 (chiral catalyst still attached to the substrate) from

Nucleophilic fluoroalkylation/cyclization route to fluorinated phthalides

• Masanori Inaba,
• Tatsuya Sakai,
• Shun Shinada,
• Tsuyuka Sugiishi,
• Yuta Nishina,
• Norio Shibata and
• Hideki Amii

Beilstein J. Org. Chem. 2018, 14, 182–186, doi:10.3762/bjoc.14.12

• synthesis of 1, we carried out the nucleophilic trifluoromethylation of 2 employing a small amount of chiral tertiary amines. However, the use of (1R,2R)-(N,N,N’,N’-tetramethyl)-1,2-diaminocyclohexane (8) as a chiral catalyst resulted in the formation of a racemic mixture of 1a (Table 2, entries 1 and 2

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• precursors and carry out the direct α-amination with a suitable electrophilic N-transfer reagent in the presence of a chiral catalyst to ensure an efficient face-differentiation in the C–N bond formation. This strategy has been investigated under chiral phase-transfer catalysis in the past and the results

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• , THF or toluene) [53][54][55][56], or in the presence of a chiral catalyst [57]. There is only one solvent and catalyst-free example [58], but in this case a long reaction time (9 h) was required. In the Pudovik synthesis of α-aminophosphine oxides, the MW-assisted accomplishment has not been utilized

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• as potential catalysts, and chiral catalyst L25 was identified as the catalyst of choice. Although no chirality transfer was observed during the reduction of 2-phenylquinoline, L25 was found to be a very active catalyst promoting transfer hydrogenation of a C=N group containing heterocycles and

Towards the development of continuous, organocatalytic, and stereoselective reactions in deep eutectic solvents

• Davide Brenna,
• Elisabetta Massolo,
• Alessandra Puglisi,
• Sergio Rossi,
• Giuseppe Celentano,
• Maurizio Benaglia and
• Vito Capriati

Beilstein J. Org. Chem. 2016, 12, 2620–2626, doi:10.3762/bjoc.12.258

• advantages in terms of reaction sustainability. In particular, the possibility to strongly reduce the amounts of organic solvent and the recyclability of the catalyst were demonstrated [23]. Moreover, in this approach, no structural modification of the precious chiral catalyst was necessary. A well-explored

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

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 chiral catalyst can bind and organize the transition state. Many examples of conjugate addition–enantioselective protonation have been reported using carbon and sulfur nucleophiles, conversely relatively few examples have been reported using amines as nucleophiles. Sodeoka and co-workers have

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

• also found that an increase of catalyst loading led to lower enantioselectivity. Similarly, Gou et al. reported the asymmetric aldol reactions of ketones with isatins catalyzed by a novel 1,2-diaminocyclohexane (DACH)-derived chiral catalyst (cat. 11, Scheme 25) [41]. The products were obtained in good

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• inherent lower reactivity and the limitations associated to the activation/coordination of these compounds to a suitable chiral catalyst. Although recently it has been shown that the problem of this low reactivity may be addressed through the development of Brønsted base catalysts with increased basicity

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• carboxamide group, in the new chiral catalyst (S)-23 the rhodium atoms are complexed to the chiral ligands by the carboxylate group, similar to those chiral complexes presented by Ikegami and coworkers (Table 1). Another important feature of this work is, unlike to the work that preceded it, that the new

• development of the chiral catalyst (S)-23 (Scheme 10). Recent studies concerning the enantioselective carbenoid insertion into C(sp3)–H bonds From 2000, the study of carbenoid chemistry has become more comprehensive. The focus of most recently published works is the development of new catalysts for carbenoid

• chiral catalyst to enantioselective carbenoid insertion into the endocyclic allylic C(sp3)–H bond. Regio- and enantioselective carbenoid insertion into the C(sp3)–H bond catalyzed by a new bulky cyclopropylcarboxylate-based chiral dirhodium complex (R)-74. Regio and diastereoselective carbenoid insertion

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• trifluoromethyl ketones were later developed using the chiral catalyst 27 (Scheme 13) [29]. The electron-deficient triazolium-derived NHC 23 mediated efficient and chemoselective cross-benzoin reactions of aldehydes and α-ketoesters to produce acyloin products endowed with a quaternary stereocentre [30

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• using boron as a chiral catalyst was a good idea. We quickly came up with a research plan over a beer or two (Figure 13). Then on our return to the UK we quickly put these ideas into practice with the investigation of a “chiral boron reagent” formed between binol and trimethoxy borate for the Lewis acid

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

• improved to 92% ee with a new chiral catalyst (Scheme 25) [65]. In 2012, Hoveyda and Jung reported a copper/NHC-catalyzed asymmetric allylic substitution of allyl phosphates with allenylboronates [66], leading to chiral allenes bearing a tertiary or quaternary carbon stereogenic center in high yields and

• allylic alkylation of terminal alkynes with primary allylic phosphates through a copper/NHC chiral catalyst system. The authors obtained chiral enynes with a tertiary stereocenter at the allylic propargylic position in good yield and with excellent enantioselectivity (Scheme 35). Conclusion Copper

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• reaction volume of 1 mL). Under these conditions the yield of allylic amine 9 doubled relative to the more dilute 1:1 reaction, to 17%; 10 and 11 were not observed. Reaction using a chiral catalyst The chiral catalyst Fe(R,R′)-PDP (6) has been used previously to promote asymmetric C–H oxidation reactions

• investigations suggest the involvement of a free nitroso species which undergoes a nitroso–ene reaction with the alkene. The intermediacy of a free nitroso species means that asymmetric induction is not observed in reactions with the chiral catalyst Fe(R,R′)-PDP (6). Experimental General experimental All

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• tripodal cage compounds (e.g., 280) by using a [2 + 2 + 2] cycloaddition reaction of branched triynes (Scheme 47). The best results for a cycloaddition were observed when triyne 279 was added dropwise over a period of 10 min to a solution of a chiral catalyst at elevated temperature (120 °C). Also, highly

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• triflates of threonine stereoisomers [47], the chiral auxiliary approach [48][49][50][51] and enantioselective hydrogenation over a chiral catalyst [52][53]. All these approaches ought to be applicable to prepare unsubstituted β-methylphenylalanine, but most if not all of them have severe drawbacks. Among

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• binaphthyl skeleton, Fu and co-workers developed the first asymmetric [3 + 2] annulation of ethyl allenoate with various α,β-unsaturated enones to provide functionalized cyclopentenes (Scheme 2) [35]. The key structural feature of the chiral catalyst B1 is its rigid binaphthyl skeleton. This approach allowed

• . Nitrogen-, phosphorus-, oxygen-, and sulfur-substituted olefins and allenamides were compatible with these B4-catalyzed reactions. Fu’s results provided useful hints for further expansion of the substrate scope. Using B2 as the chiral catalyst, Marinetti and co-workers also developed several asymmetric [3

• various aspartic acid derivatives. Using the commercially available chiral catalyst (S,S)-Et-Duphos E7, Loh and co-workers developed the asymmetric [3 + 2] annulations of phenyl allenone and furanyl allenone with electron-deficient olefins, namely enones, maleates, and fumarates, to give corresponding