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

• ) allow it to catalyze a number of organic reactions viz., nucleophilic substitutions, addition reactions, hydrogenations/hydrosilylations, cycloisomerizations, electrophilic aromatic substitutions, cross-coupling reactions, oxidative additions and reductive eliminations [66]. Iron–catalyzed C–H

• -2-carbaldehyde on the other hand resulted in appreciable yields under similar reaction conditions. The authors have successfully constructed a big library of 28 compounds with varying structure. In 2013, Gao et al. have exploited the TM-catalyzed nucleophilic addition reactions of haloalkynes 5

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

• acceptors and aldehydes [27][28][29][30][31][32], ketones [33], α-cyano esters [34][35], β-keto esters [35], β-keto acids [36], thiomalonates [37], nitroalkanes [38], oxindoles [39] and thiols [40] as Michael donors. There are only few examples of the use of sulfones as Michael donors in asymmetric addition

• 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

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• located on the surface of the polymer are capable of various addition reactions (bromination, epoxidation, oxidation) forming films of several tens or hundreds of nanometers thick on the surface. However, no further penetration of reactants into the deeper polydicyclopentadiene layers occurs [28]. It is

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• ) reaction [11][12], and rearrangement of spiro-ketones, nucleophilic substitutions of alkenes, and photochemical addition reactions. Multicomponent reactions (MCRs) are also used for the synthesis of hetero-propellanes [13][14]. Recently, heterocyclic propellanes have been reviewed [15][16]. Our group also

Synthesis and post-functionalization of alternate-linked-meta-para-[2ⁿ.1ⁿ]thiacyclophanes

• Wout De Leger,
• Koen Adriaensen,
• Koen Robeyns,
• Luc Van Meervelt,
• Joice Thomas,
• Björn Meijers,
• Mario Smet and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2190–2197, doi:10.3762/bjoc.14.192

• -elimination (route B) can easily occur, leading to reversal of the addition reactions. This was observed in a stability experiment where pure [3 + 3] macrocycle 7 in CDCl3 (without adding base) over two weeks’ time converted into a mixture of [3 + 3] macrocycle 7 (9%), acyclic oligomers (50%) and the more

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

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

• Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China 10.3762/bjoc.14.164 Abstract A number of upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives have been designed, synthesized and used as catalysts for enantioselective Michael addition reactions between

• , this may offer us the opportunity to improve the green aspect of many reactions both in organic and aqueous medium [30]. For example, it has been reported that calixarenes linked with thiourea groups can be used to catalyze asymmetric Aldol reactions or Michael addition reactions in recent years [31

• Michael addition reactions of acetylacetone and aromatic nitroalkenes. Results and Discussion Synthesis of catalysts The chemical structures and synthetic pathways for catalysts are shown in Scheme 1 and Scheme 2, respectively. A series of upper rim-functionalized calix[4]arene-based cyclohexanediamine

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• organolithium, organomagnesium, organozinc, and organochromium A, to facilitate addition reactions of appropriate carbon electrophiles such as aldehydes (Scheme 1, top) [1]. In contrast, π-electrophilic carbon-connected late transition metals B facilitate the carbometalation of carbon–carbon multiple bonds

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

• nucleophiles, thus increasing the structural diversity of the resulting products. The first asymmetric catalytic versions were reported only in the 2010s despite tremendous achievements in catalytic asymmetric imine addition reactions [20][21][22]. Ever since, a number of catalytic asymmetric nucleophilic

Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

• Koichi Mitsudo,
• Junya Yamamoto,
• Tomoya Akagi,
• Atsuhiro Yamashita,
• Masahiro Haisa,
• Kazuki Yoshioka,
• Hiroki Mandai,
• Koji Ueoka,
• Christian Hempel,
• Jun-ichi Yoshida and
• Seiji Suga

Beilstein J. Org. Chem. 2018, 14, 1192–1202, doi:10.3762/bjoc.14.100

Addition of dithi(ol)anylium tetrafluoroborates to α,β-unsaturated ketones

• Yu-Chieh Huang,
• An Nguyen,
• Simone Gräßle,
• Sylvia Vanderheiden,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2018, 14, 515–522, doi:10.3762/bjoc.14.37

• at rt [33], reactions with 3e and 3g (R2 = iPr, Ph) required a reaction time of 13 h. As addition reactions of ketene dithioacetals bearing EWGs in α-position have been described earlier, we used the electrophile 3d for a comparison of those literature-known procedures with our experiments using non

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• state A are the major products of the aldol addition reactions. As mentioned above, aldol addition products were not isolated from the reaction of 1 with electron rich p-methyl-, p-methoxy-, and p-ethoxybenzaldehydes. Here, aldol condensation products 4g–i were obtained as single isomers after

• conditions and application of enantiopure Lewis acids or SF5-substituted acetamides bearing a chiral auxiliary will result in asymmetric aldol addition reactions in the future. Conclusion From octyl SF5-acetate and TMSOTf/Et3N, a (Z)-enolate (ketene silylacetal) was preferentially formed as has already been

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• afford the corresponding octa-1,7-diene 5a in only 46% yield. In this case, the 5-membered lactol derivative 8a was also obtained in 42% yield as a side-product. A proposed reaction mechanism for the formation of 5a and 8a is shown in Scheme 3. Thus, the nucleophilic addition reactions of vinylmagnesium

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

• resulting imines (7r−t) are hydrolyzed under the current reaction conditions. Notably, imines 7n [42][43][44][45] and 7t [46][47][48] are useful imines for diastereoselective 1,2-addition reactions. Following these substrate scope studies, we next examined the quinone-catalyzed C–C bond cleavage of

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• to suppress side reactions and to use a stoichiometric amount of nucleophile. Under these conditions, Michael addition reactions with nitrosoalkenes can be realized in an intramolecular fashion that opens access to complex bridged and fused carbocyclic frameworks bearing several contiguous

• Stabilized enolates and their equivalents are the most studied C-nucleophiles in Michael addition reactions with nitrosoalkenes. A first systematic study in this area was done by Ohno and co-authors [13][23], who reported the addition of diethyl malonate and acetylacetone anions to cyclic nitrosoalkenes

Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides

• Ryota Miyaji,
• Yuuki Wada,
• Akira Matsumoto,
• Keisuke Asano and
• Seijiro Matsubara

Beilstein J. Org. Chem. 2017, 13, 1518–1523, doi:10.3762/bjoc.13.151

• significantly contributed to the field of asymmetric synthesis [1][2][3][4][5][6]. In these catalysts, (thio)urea and tertiary amino functional groups cooperatively activate a nucleophile and an electrophile simultaneously, in a suitable spatial configuration. Thus, they enable various stereoselective addition

• reactions to occur. Organocatalysts have also been employed in several asymmetric cyclization reactions via intramolecular hetero-Michael addition [7][8][9][10][11][12][13][14][15][16]. In these reactions, multipoint recognition by the catalysts favors the specific conformations of the substrates in the

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• applications of alkynyl selenides are electrophilic addition reactions, many of them modulated by transition-metal catalysts [11]. Some examples are: hydroboration which results in a vinylborane selenide used in Pd-catalyzed Suzuki cross-coupling reactions [12], the addition to tributyltin hydride in the

• presence of Pd and Cu catalysts to afford (E)-α-selenylstannanes for the synthesis of trisubstituted alkenes [13] and hydrozirconation with further replacement of Zr atom by hydrogen or halogen [14] or their use in the preparation of α-seleno-α,β-unsaturated ketones [15]. Besides, hydrogen halide-addition

• reactions to alkynyl selenides in the absence of transition metals [16] and the addition of p-toluenesulfonic acid [17] are applied to obtain vinyl organometallic compounds and key selenoester intermediates. Finally, electrophilic cyclizations [18][19] of systems bearing a selenide alkynyl group allow the

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• addition reactions mainly focused on allylation, propargylation, alkenylation and alkylation of aldehydes [10][11]. Since the first example of enantioselective allylation of aldehydes catalyzed by a Cr(II)–salen complex in 1999 by Cozzi and co-workers [12], several elegant catalytic enantioselective

A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• cross-coupling reactions, cycloaddition reactions, radical reactions and reductive addition reactions. A terminal alkyne can also react as nucleophile or serve as synthon for pyrrole rings [24][25]. Thus we here fuse the rich alkyne chemistry to the EDOT backbone, resulting in a novel EDOT derivative

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

• [6], allylation [7], conjugate addition to enones [8], and γ-addition with allenoates [9]. All these examples focused on nucleophilic addition reactions of the C5 atom of 5H-thiazol-4-ones. Recently, we described an organocatalytic asymmetric [4 + 2] cyclization of 5H-thiazol-4-ones with a series of

Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107

• addition in more general terms and analyzed the addition reactions of allylmagnesium bromide both to 29 and 30. Notably, this route would allow to access all possible stereoisomers of the manzacidins, in agreement with the stereochemical diversity of this class of natural products. In detail, the synthesis

Bifunctional catalysis

• Darren J. Dixon

Beilstein J. Org. Chem. 2016, 12, 1079–1080, doi:10.3762/bjoc.12.102

• molecules possessing two distinct functional groups to bring about new reactivity and/or selectivity in a reaction of interest. The reactions are typically polar addition reactions of pronucleophiles and electrophiles where, ideally, simple low-cost starting materials are converted into high-value

• reactivity and selectivity in synthetically relevant reactions. Furthermore, owing to the great number of pronucleophiles and electrophiles that are available, the number of polar addition reactions that are amenable to catalysis through the action of bifunctional catalysts is enormous, and consequently, 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

• same group reported the organocatalytic asymmetric addition reactions of isatins with electron-rich aromatics sesamols using the cinchona alkaloid-derived thiourea catalyst (cat. 17) under mild conditions. In the presence of 10% catalyst, sesamols reacted with isatins smoothly in tert-butyl ether at

• corresponding (R)-3-aryl-3-hydroxyoxindoles in good yields (up to 87% yield) and with excellent enantioselectivity (up to 92% ee, Scheme 31) [48]. This slightly modified protocol was then successfully applied to the addition reactions of 1-naphthols and isatins, affording the desired products in slightly lower

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

• )-ones 1 as pronucleophiles in organocatalyzed Michael addition reactions 2-Thio-1H-imidazol-4(5H)-ones 1 (R = SBn) have been reported to be effective equivalents of N-subtituted (alkyl, aryl, allyl) α-amino acids in conjugate addition reactions to both, nitroalkenes and α-silyloxy enones as Michael

• reactions. 2.2.1 Michael addition reactions, nitroalkenes as acceptors. The first example of the utility of the thiazol-4(5H)-ones 2 as pronucleophiles in asymmetric catalysis was reported in 2013 in the Michael addition to nitroalkenes catalyzed by the bifunctional ureidopeptide-like Brønsted base C5

• . Chiral phosphine-mediated nucleophilic catalysis has attracted considerable attention in the recent years [98][99][100][101]. However, few examples of phosphine-mediated γ-addition reactions have been reported. Pioneering studies on γ-additions of pronucleophiles to allenoates or alkynoates were first

Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

• Qiao-Wen Jin,
• Zhuo Chai,
• You-Ming Huang,
• Gang Zou and
• Gang Zhao

Beilstein J. Org. Chem. 2016, 12, 725–731, doi:10.3762/bjoc.12.72

• a variety of reactions such as aza-Morita–Baylis–Hillman reactions [19][20][21], Rauhut–Currier reactions [22][23][24][25][26][27], Michael addition reactions [28][29][30][31][32][33][34][35], and various cycloadditions [36][37][38][39]. In recent years, our group has focused on the development of