A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• efficient organocatalysts due to their variable interacting sites. In this context, substituted calixarenes, cyclodextrins, etc., substances known for their ability to encapsulate organic guest molecules, have been explored as organocatalysts over the last two decades [19][20][21][22][23][24]. Another class

• environmentally oriented efficient organocatalysts with prominence “on-water conditions” [30][31]. It is known that an important condition for an organic reaction in water is the aggregation of the reactants and the catalyst by hydrophobic forces. Further, the potential of hydrogen-bond donation may be a vital

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• , which allows to obtain chiral cyclic sulfones with high enantioselectivity [10][11][12]. Also non-racemic cyclic sulfones can be obtained by the Diels–Alder reaction, catalyzed by chiral Lewis acids or organocatalysts. Rh- and Cu-catalyzed CH-insertion reactions occurring at moderate or high

• reactions. Thus, ketonitrosulfones were obtained with good enantiomeric excesses via asymmetric addition of α-nitrosulfones to enones in the presence of organocatalysts [41]. Asymmetric addition of β-ketosulfones to nitroalkenes was implemented using various organocatalysts [42]. The reaction of

• ketosulfones with nitroalkenes in the presence of organocatalysts shows high enantioselectivity, however, leads to a mixture of diastereomers. For the catalytic activation of β-ketosulfones by metal complexes chiral Lewis acids may be considered as an alternative way to carry out the asymmetric Michael

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• desirable especially if such catalysts work well with a wide range of C-, O-, N- and S-nucleophiles under mild conditions. We also noted that the use of organocatalysts to catalyze the Ferrier rearrangement is scarcely reported. Recently, organoboron-catalysis emerged as a mild and effective strategy for

Ugi reaction-derived prolyl peptide catalysts grafted on the renewable polymer polyfurfuryl alcohol for applications in heterogeneous enamine catalysis

• Alexander F. de la Torre,
• Gabriel S. Scatena,
• Oscar Valdés,
• Daniel G. Rivera and
• Márcio W. Paixão

Beilstein J. Org. Chem. 2019, 15, 1210–1216, doi:10.3762/bjoc.15.118

• -supported chiral organocatalysts usually provides a much greener prospect for the synthesis of enantiomerically enriched building blocks [4][5][6]. Importantly, immobilized catalysts allow for both recyclability of the catalyst and the implementation of continuous-flow procedures, which usually encompass

• high reaction yields and reduction of waste – aspects recognized as compatible with the principles of green chemistry [1][2][3][4][5].. However, almost all polymers used in the development of supported organocatalysts are made from non-renewable sources and composed of non-biodegradable materials (e.g

• ., polystyrene) [1][2][3]. When aiming at implementing large-scale catalytic processes with supported organocatalysts, a relevant “green” premise is the use of renewable and readily available solid supports [1][2][3][4][5]. Accordingly, we envisioned the utilization of the polymer polyfurfuryl alcohol (PFA

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• generation of new chiral centres. This drawback needs to be addressed so that new ligands and organocatalysts can be discovered and applied to the synthesis of enantiomerically pure γ-lactams of this type under smooth and environmentally more benign reaction conditions. Another area of improvement is the

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant

• polymerization of cyclic carbonates, such as trimethylene carbonate (TMC) and its derivatives have been used for the controlled synthesis of high-molecular weight polymers. Among many catalysts, organocatalysts have attracted considerable attention, since the use of nontoxic catalysts warrants a safe use in

• biomedical applications [24]. The amidine base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is one of the best studied and most popular organocatalysts for ring-opening polymerizations of cyclic carbonates and lactones [25][26][27]. In contrast to the high activity of lactone polymerization, cyclic carbonate

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• formation of a supramolecular structure whereas that of 6, containing additional CF3 substituents, shows the formation of a monomeric structure. Diols 1–6 were found to be active organocatalysts in oxo-Diels–Alder reactions in which 2 recorded a 72% ee with trimethylacetaldehyde as a substrate. Keywords

• library of aldehydes (aromatic: 97–99% ee; aliphatic: 84–98% ee) [28]. Thereafter, many different kinds of hydrogen bonding-based organocatalysts have been developed for oxo-DA reactions [29][30][31][32][33][34][35]. One kind of organocatalyst in particular, which is based on an oxazoline template with

• hydroxy and NH units for hydrogen bonding activation, % ee and yields in oxo-DA reactions were found to be enhanced with increasing NH acidity, leading to stronger hydrogen bonds [32]. So, there is much room for further investigation and improvement with other hydrogen bonding organocatalysts. An earlier

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• , Czech Republic 10.3762/bjoc.15.80 Abstract The preparation of new organocatalysts for asymmetric syntheses has become a key stage of enantioselective catalysis. In particular, the development of new cyclodextrin (CD)-based organocatalysts allowed to perform enantioselective reactions in water and to

• ; cinchona alkaloids; CuAAC click reaction; cyclodextrin; organocatalysts; Introduction Cyclodextrins (CDs) [1], cyclic oligosaccharides consisting of α-D-glucopyranoside units, and their derivatives are widely used in many industrial and research areas for their ability to form supramolecular inclusion

• as the promoter (not in a catalytic amount) of a Henry reaction and obtained the product with 99% ee. Subsequently, Doyagüez et al. [17] attached L-proline to β-CD via different linkers (including a triazole linker) and used the resulting organocatalysts in an aldol reaction in water, albeit with a

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

• Hong Yan,
• Zhong-Yi Mao,
• Zhong-Wei Hou,
• Jinshuai Song and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

• the biaryls with good to excellent central-to-axial chirality transfer. Keywords: axial chirality; biaryl; electrochemistry; oxidation; radical; Introduction Axially chiral biaryls are prevalent in natural products, bioactive molecules and organocatalysts [1][2]. Among the many methods that have

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• thiols (Scheme 1) [17][18][19][20][21], other methodologies employing different sulfur sources such as disulfides or silylsulfides have been described, which most of them involves metals, e.g., indium [22], copper [23], mercury [24], or organocatalysts [25]. β-Ketosulfides, in addition, play an important

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• transition metals, Lewis acids, and organocatalysts has been productively utilized in asymmetric transformations [7][8][9], cross-couplings [10][11][12], and oxidative decarboxylation reactions [13][14], among others. The use of a cocatalyst to control these photochemical transformations enables reactions

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• oxidative and reductive cycle can be observed and the two routes are even in competition and occur simultaneously. This is reinforced by remarkably long lifetime excited state (Table 8). In organic chemistry, TADF molecules can also be used as organocatalysts for classical organic reactions that are

• hydrocarbons [93], heteropolyacenes [90][91], carbazoles [80][81][94], triazines [95], pentacenes [96], diketopyrrolopyrroles [24] and perylene [97][98] derivatives have been investigated as organocatalysts as exemplified in Scheme 5. 3 Comparison of the efficiency of these photoredox catalysts in

• cycles involved with iodonium salt and (A) (TMS)3SiH, (B) NVK and (C) EDB. Structures of additives involved in the photoredox catalytic cycles. Structures of photoredox metal-based catalysts. Photocatalytical cycle for the Ru complex. Structures of photoredox organocatalysts. Diversity of the chemical

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

• Iveta Tichá,
• Gábor Benkovics,
• Milo Malanga and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

• selected positions remains a challenging task because of the similar reactivity of the hydroxy groups. Nevertheless, selectively disubstituted CD derivatives are used to prepare artificial enzymes [4][5], metallocatalysts and organocatalysts [6][7][8] or amino acid mimics [9]. Among the methods used to

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

• Zheng-Yi Li,
• Hong-Xiao Tong,
• Yuan Chen,
• Hong-Kui Su,
• Tangxin Xiao,
• Xiao-Qiang Sun and
• Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

• and yields of the Michael reactions. Supramolecular catalysis has drawn tremendous interest in the past few years [15][16][17][18][19][20][21][22][23]. In this context, calixarenes are ideal supramolecular macrocyclic scaffolds for the design of molecular receptors and organocatalysts due to their

• reactions in aqueous solution with excellent enantioselectivity [35]. As part of our ongoing studies to develop novel types of organocatalysts for asymmetric catalysis, in this study, we aimed to synthesize novel upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives to catalyze asymmetric

• the new chiral amino-substituted thioureas [33][39]. For this, the Michael addition reaction of acetylacetone (8) to β-nitrostyrene (7a) was chosen as the model reaction to evaluate the efficiency of compounds 1–4 as chiral organocatalysts (Table 1, entries 1–4). From Table 1, it can be seen that the

Thiocarbonyl-enabled ferrocene C–H nitrogenation by cobalt(III) catalysis: thermal and mechanochemical

• Santhivardhana Reddy Yetra,
• Zhigao Shen,
• Hui Wang and
• Lutz Ackermann

Beilstein J. Org. Chem. 2018, 14, 1546–1553, doi:10.3762/bjoc.14.131

• motifs of powerful transition metal catalyst ligands and organocatalysts (Figure 1) [94][95][96][97]. During the preparation of this article, the use of strongly-coordinating, difficult to remove directing groups has been reported [70][71]. In sharp contrast, notable features of our approach include (i

• thermal fashion as well as by means of mechanochemistry, providing access to synthetically meaningful aminoketones. Selected ferrocene-based ligands and organocatalysts. Scope of substituted dioxazolones 2. C–H Amidation of arylated ferrocenes 1. Thiocarbonyl-assisted C–H amidation. H/D Exchange reactions

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• investigated and significant achievements have been reported making iodine compounds now useful organocatalysts in asymmetric synthesis (reaction 2 in Scheme 1a) [15][16][17][18][19][20][21][22][23][24]. In parallel to these investigations, a third strategy has been envisaged with the development of tandem

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

• -cyclohepten-1-one and chalcone were also tested as substrates for the Michael addition reaction and the corresponding adducts were obtained in good yield with moderate enantioselectivity (13–23% ee). Calixarene-derived thiourea seemed to be an interesting backbone for design of new organocatalysts for

• series of calixarene-based chiral bifunctional tertiary amine–thiourea organocatalysts 54–56 have been synthesized by us and Genc et al. (Scheme 15) [52][53]. Among them, 54a,b were applied to the asymmetric Michael addition of 1,3-dicarbonyl compounds 34 and 57 to a variety of nitroolefins. Although

• . reported the synthesis of a series of prolinamide and hydroxyprolinamide organocatalysts based on the calix[4]arene scaffold (Figure 8) [59]. Treatment of Boc-protected-L-proline or hydroxyproline with various aminocalix[4]arenes under one of the appropriate coupling conditions and subsequent deprotection

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• –Hillman reactions, Friedel–Crafts reactions, aza-Henry reactions, domino reactions initiated by nucleophilic additions to isatin imines, and miscellaneous reactions. Most of the reactions depicted in this review have been promoted by a wide variety of chiral organocatalysts but chiral metal catalysts have

• ]. An extensively used two-component variant of this reaction consists in using a preformed imine. Among chiral metal complexes, a wide variety of organocatalysts [26][27][28][29][30][31][32][33][34] has been used to promote asymmetric Mannich reactions. Among them, cinchona alkaloid 1 was employed in

• , ECA109 and BT474 cancer cell lines. Metal-catalyzed reactions In addition to organocatalysts, chiral metal catalysts [41][42][43][44][45][46][47] have been recently applied to promote enantioselective Mannich reactions. As an example, in 2015 Feng et al. reported the enantioselective Mannich reaction of

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation

• Takayuki Yakura,
• Tomoya Fujiwara,
• Akihiro Yamada and
• Hisanori Nambu

Beilstein J. Org. Chem. 2018, 14, 971–978, doi:10.3762/bjoc.14.82

• iodobenzene and 4-iodobenzenesulfonic acid (12) as catalysts [58][59]. As part of our study on the development of multifunctionalized organocatalysts based on hypervalent iodine chemistry [60][61][62][63][64][65][66], we found that N-isopropyl-2-iodobenzamide (13), when utilized as a catalyst with Oxone® at

• partially supported by a Grant-in-Aid for Scientific Research on Innovative Areas “Advanced Molecular Transformations by Organocatalysts” from the Ministry of Education, Culture, Sports, Science and Technology, Japan; JSPS Core-to-Core Program, B. Asia-Africa Science Platforms; and Toyama Prefecture

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• (enzymes), organocatalysts and metal catalysts [47]. Catalysis is defined as heterogeneous when catalysts are in an aggregated state, and are thus in a different phase than the reactants [27][48]. Heterogeneous catalysts typically consist of a solid carrier, the so called “support”, on which catalytic

• hydrophobic and aqueous compartments, they are especially useful for the immobilization of different catalysts, such as organocatalysts and enzymes that require different microenvironments for their optimal performance. 3. Covalent systems 3.1. Dendrimers Dendrimers are a class of highly branched molecules

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

• reactions implying the use of a chiral auxiliary resulted effectively in various optically pure compounds [10][18][19][20]. Second, enantioselective syntheses of these bicylic lactams were performed by using chiral transition metal- or organocatalysts which control the configuration of the trisubstituted

• , substituted at the benzyl para-position by isopropyl and CF3 groups, gave good results with 76 and 74% de (Table 2, entries 9 and 10). Dimeric and trimeric organocatalysts 19 and 20 based on a cinchonine core did not enhance the reaction diastereoselectivity (Table 2, entries 15 and 16). Finally, by

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• catalyst. Furthermore, specific organocatalysts can provide respective stereoisomers of the key Michael adduct in up to 99:1 er. Keywords: kinetic resolution; Michael addition; organocatalysis; pregabalin; squaramide; Introduction Asymmetric organocatalysis has considerably broadened possibilities for

• malonate catalyzed by hydrogen-bond-donating organocatalysts (Scheme 2). We have also briefly investigated Meldrum´s acid as a donor, instead of dimethyl malonate, but we have obtained a complicated reaction mixture, which was difficult to purify. Therefore, we have focused our attention on the Michael

• addition of dimethyl malonate. An initial catalyst screening was performed in dichloromethane, based on our previous experiences with this type of Michael additions [18]. We have employed a range of squaramide and thiourea organocatalysts C1–C7 [18][27][28][29][30][31][32][33][34], as well as two newly

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• Lingjun Xu Shuwen Han Linjie Yan Haifeng Wang Haihui Peng Fener Chen Department of Chemistry, Fudan University, Shanghai 200433, PR China 10.3762/bjoc.14.19 Abstract A family of novel chloramphenicol base-amide organocatalysts possessing a NH functionality at C-1 position as monodentate hydrogen

• bond donor were developed and evaluated for enantioselective organocatalytic alcoholysis of meso-cyclic anhydrides. These structural diversified organocatalysts were found to induce high enantioselectivity in alcoholysis of anhydrides and was successfully applied to the asymmetric synthesis of (S

• )-GABOB. Keywords: alcoholysis desymmetrization; bifunctional organocatalysis; chloramphenicol base; Introduction Over the past decade, remarkable advances in the utilization of natural products as chiral structural motifs for the design of bifunctional organocatalysts have been achieved. A high

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

• Xinyun Liu,
• Johnny H. Phan,
• Benjamin J. Haugeberg,
• Shrikant S. Londhe and
• Michael D. Clift

Beilstein J. Org. Chem. 2017, 13, 2895–2901, doi:10.3762/bjoc.13.282

• decarboxylative homologation of α-amino acids [32], which demonstrated for the first time that quinone organocatalysts can be utilized to enable oxidative C–C bond cleavage to provide versatile imine intermediates. To further exploit the utility of this chemistry, we sought to develop a new method for the

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• in general have been proven excellent stereoselective organocatalysts [33][34][35][36][37][38][39][40]. In particular, CA derivatives bearing proline units (on both the upper and the lower rim) have been tested as catalysts for asymmetric aldol reactions in water [28][29][30][33]. Similar derivatives