Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• acids producing chiral isotetronic acids. However, the application of compound IV as the organocatalyst in these reactions proceeded sluggishly, and the corresponding products were obtained in only moderate ees [24]. Herein, the aldol reaction was chosen as a standard asymmetric reaction to explore the

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

• central chirality information to the axial chirality to give the chiral biaryldiols (Scheme 3) [14]. In 2013, Akiyama and co-workers described the enantioselective preparation of multisubstituted biaryls by the desymmetrization strategy, which was further enhanced by the subsequent asymmetric reaction

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• given combination of enone and arylboronic acid. Keywords: asymmetric reaction; boronic acid; conjugated enones; chromones; enantioselective catalysis; Michael addition; Pd complexes; Introduction The asymmetric 1,4-addition of arylboronic acids to conjugated cyclic enones and chromones is a very

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• generate CF3-substituted iminium ions able to promote Friedel–Crafts alkylations [110][111]. Ma et al. exploited this mode of activation in a Brønsted acid-catalyzed three-component asymmetric reaction [112]. Mixing hemiacetal 175, arylaniline 176, and indole derivatives 149 in the presence of a catalytic

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• diminish with extended reaction time and the yield of the room temperature reaction could be increased to 70% by extending the reaction time from 48 h to 120 h (Table 1, entry 4). The asymmetric reaction was found to be most effective at 23 °C (Table 1, entries 3 and 4). Unfortunately, attempts to lower

• as the optimized reaction conditions. With optimized reaction conditions in hand, we set out to explore the scope and limitations of the asymmetric reaction (Scheme 1). Initially, we examined the reaction of various anilines with furylcarbinol 1a. Scheme 1 summarizes the results obtained with ortho

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• , could promote the Diels–Alder reaction with anthracenes and various unsaturated carbonyl compounds under mild conditions [13]. The use of latent carbocation catalysis with TP was examined in order to achieve enantioselective control. To our delight, TP catalyzed the asymmetric reaction affording

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

• close chiral anion-pair complexes would then undergo a chiral counterion-controlled asymmetric reaction with a nucleophile. This proposal was validated experimentally, and a chloride-induced conformational switch to form a helical backbone was experimentally observed by circular dichroism (CD) during

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• to afford a spirocyclic sulfur-bridged N-heterocycle 4 in 70% yield and without compromising its ee value. Conclusion In conclusion, we have developed the first asymmetric reaction of 5H-thiazol-4-ones with N-itaconimides. By employing a DP-UAA catalyst, the reaction undergoes a [4 + 2] annulation

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

Development of chiral metal amides as highly reactive catalysts for asymmetric [3 + 2] cycloadditions

• Yasuhiro Yamashita,
• Susumu Yoshimoto,
• Mark J. Dutton and
• Shū Kobayashi

Beilstein J. Org. Chem. 2016, 12, 1447–1452, doi:10.3762/bjoc.12.140

• . Compared with the chiral CuOTf/Et3N system, the CuHMDS system showed higher reactivity, and the desired reactions proceeded in high yields and high selectivities with catalyst loadings as low as 0.01 mol %. Keywords: [3 + 2] cycloaddition; asymmetric reaction; catalytic reaction; low catalyst loading

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

• Haipan Zhu,
• Peile Du,
• Jianjun Li,
• Ziyang Liao,
• Guohua Liu,
• Hao Li and
• Wei Wang

Beilstein J. Org. Chem. 2016, 12, 1340–1347, doi:10.3762/bjoc.12.127

• important challenges. To the best of our knowledge, so far merely two catalyst manifolds have been realized to effect the transformations with C=C double bonds instead of C=O in the α,β-unsaturated systems. Tsuji described the first organometallic promoted non-asymmetric reaction between D–A cyclopropanes

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

• = S) analogues of these oxazol-4(5H)-ones have been demonstrated to be very interesting templates in asymmetric catalysis. In these cases the hydrolysis of the adducts coming from an asymmetric reaction can provide enantioenriched α-hydroxy acids (X = O), N-substituted α-amino acids (X = NR’) or α

• ]. The main advantages of these pronucleophiles over the previous known templates are: i) the NR group can be installed in the heterocycle previous to the asymmetric reaction, ii) they are easily deprotonated under soft enolization conditions (aromatic enolate formation), and iii) unlike azlactones and

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• cinchona class of alkaloids are a dynamic and versatile type of organocatalyst that should be included in the screening libraries of chemists seeking to develop asymmetric methodologies. Review Morita–Baylis–Hillman (MBH) and MBH-carbonate reactions The first reports of an asymmetric reaction catalyzed by

• the two enantiomers of 32 will react more rapidly with nitromethane in the presence of the cupreidine catalyst CPD-33. As these enantiomers equilibrate via 35 in the presence of the catalyst, a dynamic kinetic asymmetric reaction occurs (Scheme 9b). Friedel–Crafts reaction Pedro and co-workers have

Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

• Ming-Liang Zhang,
• Deng-Feng Yue,
• Zhen-Hua Wang,
• Yuan Luo,
• Xiao-Ying Xu,
• Xiao-Mei Zhang and
• Wei-Cheng Yuan

Beilstein J. Org. Chem. 2016, 12, 295–300, doi:10.3762/bjoc.12.31

• work represents the first example of 1H-pyrrole-2,3-diones used as Henry acceptors for the asymmetric reaction. Herein, we report our preliminary results on this subject. Results and Discussion We started our studies with the reaction of ethyl 1-benzyl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrole-3

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

Efficient synthesis of dihydropyrimidinones via a three-component Biginelli-type reaction of urea, alkylaldehyde and arylaldehyde

• Haijun Qu,
• Xuejian Li,
• Fan Mo and
• Xufeng Lin

Beilstein J. Org. Chem. 2013, 9, 2846–2851, doi:10.3762/bjoc.9.320

• reaction conditions.a One-pot synthesis of dihydropyrimidinones.a Optimization of the asymmetric reaction conditions.a Supporting Information Supporting Information File 580: Experimental details and spectroscopic data. Acknowledgements This work was supported by the National Natural Foundation of China

Cascade radical reaction of substrates with a carbon–carbon triple bond as a radical acceptor

• Hideto Miyabe,
• Ryuta Asada and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2013, 9, 1148–1155, doi:10.3762/bjoc.9.128

• cascade process, the reactions of propiolic acid derivatives 7 and 8 were tested (Scheme 4). At first, the reaction of 7 was evaluated under asymmetric reaction conditions. However, the cascade addition–cyclization–trapping reaction did not proceed, and the simple adduct 10 was formed in 57% yield by the

• via the intermediate radical F (Scheme 5). The reaction was carried out in the presence of Bu3SnH under asymmetric reaction conditions. Although the reaction proceeded even at −78 °C, the nearly racemic product 13 was isolated in 60% yield. This observation indicates that the regiochemical course of

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• (5), followed by an intramolecular aldol reaction and final dehydration to give the desired chromene derivative. Related work involving asymmetric reaction of salicylaldehyde derivatives and α,β-unsaturated carbonyl compounds in the synthesis of 2-phenylchromenes was reported by Li and co-workers

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• reaction conditions described for 6a were also successful for 2,2-diphenylacetic acid (6b) and even an asymmetric reaction product could be formed through a mixture of phenylacetic acid (6a) and diphenylacetic acid (6b), although in smaller yield. Hypervalent iodine compounds can be used in organic

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• coupling reactions and a Au-catalyzed asymmetric reaction, respectively. Suzuki–Miyaura and Heck–Mizoroki coupling reactions catalyzed by NHC–Pd(II) complex The Pd-catalyzed coupling reaction is one of the most powerful methods for the formation of carbon–carbon bonds in organic synthesis [60][61][62][63

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• stereoretentive CF3 transfer. High enantioselectivities in the range 93–97% were measured for the corresponding alcohols because of post-reaction racemization of aldehydes. Although the scope of this asymmetric reaction is limited to aldehydes, the level of enantioselectivity is superior to that obtained in the

Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approach

• Shaimaa El-Fayyoumy,
• Matthew H. Todd and
• Christopher J. Richards

Beilstein J. Org. Chem. 2009, 5, No. 67, doi:10.3762/bjoc.5.67

• almost always known for any given catalytic, asymmetric reaction, and yield, ee and mol % are used in their standard forms (i.e. as percentages). Values for ACE may be obtained for any given catalytic system, and several well-known reactions are shown in Table 1. The primary criterion used for selecting

• a comparison of reactions commonly described in the academic chemical literature, the main emphasis of this commentary is on a consideration of atom economy applied to an asymmetric reaction. Thus a small ligand with few atoms able to catalyse a reaction as effectively as a larger ligand requiring

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• in continuous flow asymmetric reactions using immobilized catalyst systems. An asymmetric reaction that has been examined extensively in continuous flow using supported catalysts is the enantioselective addition of diethylzinc to benzaldehyde [23][24][25][26][27][28]. A fast, single pass continuous

• ketone was investigated in flow using polystyrene-supported cinchonine and cinchonidine 27 (Scheme 8) [33]. A fluid bed reactor was devised for this asymmetric reaction, which allowed for the polymer beads to move around freely. Solutions of the reagents were introduced into the bottom of the column bed

Enantioselective nucleophilic difluoromethylation of aromatic aldehydes with Me₃SiCF₂SO₂Ph and PhSO₂CF₂H reagents catalyzed by chiral quaternary ammonium salts

• Chuanfa Ni,
• Fang Wang and
• Jinbo Hu

Beilstein J. Org. Chem. 2008, 4, No. 21, doi:10.3762/bjoc.4.21

• [36] or asymmetric synthesis of α,β-epoxysulfones [37], they were not as effective as 4-trifluoromethylphenyl functionality in the current asymmetric reaction (Table 2, entries 13, 15 and 16). In the light of these results, we next examined the substrate scope of this enantioselective