Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• . Unlike Table 1, entry 1, which was taken to completion, bromochlorinations quenched at low conversion exhibited high enantioselectivity for 6, but also constitutional isomer ratios (cr) as low as 2:1 for 6:7 (not shown). These observations are consistent with a highly selective catalytic reaction

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• AgBF4 was used in place of AgOAc under optimized conditions for C–H arylation with aryl iodides, HBF4 (or any other added acid) was unnecessary for the catalytic reaction to occur. Here, since AgBF4 apparently reacts with I–Pd+BF4− to produce catalytically active Pd2+(BF4)2− (Scheme 22), and there are

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

• adducts after catalytic reaction and hydrolysis. 1H-Imidazol-4(5H)-ones 1 and thiazol-4(5H)-ones 2. Proposed model for the Michael addition of 1H-imidazol4-(5H)-ones and selected 1H NMR data which support it [55]. Ureidopeptide-like Brønsted bases: catalyst design. a) Previous known design. b) Proposed

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• of 71%. The suggested mechanism for this catalytic reaction involves a bifunctional activation. Utilizing the primary amino group, the authors proposed that the catalyst condenses to form an imine, which is in equilibrium with the corresponding enamine of isobutyraldehyde, while the two hydrogens of

• the thiourea group interact with one or two carbonyl groups of phenylbutenoate 2 (Scheme 5). Another catalytic reaction catalyzed by a primary amine-thiourea that leads to multiple chiral centers is the asymmetric desymmetrization of 4,4-disubstituted cyclohexadienones 5, using the Michael addition of

• ethyl malonate, producing the active nucleophile, while the thiourea group activates the electrophile (Scheme 6). The above catalytic reaction provided products with yields up to 99%, dr up to 93:7 and ee up to 93%. Carter and co-worker utilized a similar primary amine-thiourea, organocatalyst 11, in an

Versatile deprotonated NHC: C,N-bridged dinuclear iridium and rhodium complexes

• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 117–124, doi:10.3762/bjoc.12.13

• effective for any catalytic reaction, but some successful applications were achieved in the field of Ru-catalyzed metathesis of olefins [9][10][11][12], Ir-catalyzed hydrogenation [13][14], Pd-catalyzed C=C coupling reactions [15][16], Ir-catalyzed CO2 fixation [17][18], and/or functionalization of alkenes

Comparison of the catalytic activity for the Suzuki–Miyaura reaction of (η⁵-Cp)Pd(IPr)Cl with (η³-cinnamyl)Pd(IPr)(Cl) and (η³-1-t-Bu-indenyl)Pd(IPr)(Cl)

• Patrick R. Melvin,
• Nilay Hazari,
• Hannah M. C. Lant,
• Ian L. Peczak and
• Hemali P. Shah

Beilstein J. Org. Chem. 2015, 11, 2476–2486, doi:10.3762/bjoc.11.269

• described in Figure 2 and Figure 3. Peaks consistent with the formation of CpDim are observed during catalysis, and approximately 40% of the Pd is in the form of CpDim upon completion of the catalytic reaction. In contrast, for Cin under the same conditions, only a small amount of Pd was determined to be in

Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2015, 11, 1944–1949, doi:10.3762/bjoc.11.210

• (non-catalytic) reaction, 1H NMR analysis of the crude reaction mixtures showed greater conversion of indole and less byproducts for the catalyzed reaction compared to the thermal reaction. We optimized the catalytic reaction conditions and found that dropwise addition of an ice-cooled solution of Br

Asymmetric 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators via monocarbinol functionalization. Ready access to polyrotors

• Cyprien Lemouchi and
• Patrick Batail

Beilstein J. Org. Chem. 2015, 11, 1881–1885, doi:10.3762/bjoc.11.202

• variety of functionalization sequences of BCO rotators by performing nucleophilic reactions on the terminal alkyne [16] as well as Sonogashira coupling reactions [17]. One way to synthesize 1 is via a catalytic reaction to achieve the deprotection of a single 2-methyl-3-butyn-2-ol and transform the

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• 2 and 3 are a bit better than 1 for this transformation. The trans-effect of carbene ligand may promote the substitution of trans-positioned acetonitrile ligand by other substrates in the catalytic reaction. Since complexes 2 and 3 are found to be the efficient catalysts for transfer hydrogenation

Towards inhibitors of glycosyltransferases: A novel approach to the synthesis of 3-acetamido-3-deoxy-D-psicofuranose derivatives

• Maroš Bella,
• Miroslav Koóš and
• Chun-Hung Lin

Beilstein J. Org. Chem. 2015, 11, 1547–1552, doi:10.3762/bjoc.11.170

• , the insertion of an N-acetylglucosaminyl moiety (GlcNAc-) into an oligosaccharide chain was identified as the crucial step catalyzed by N-acetylglucosaminyltransferases (GnTs) in the presence of a metal co-factor. In this catalytic reaction, UDP-GlcNAc [uridine 5′-(2-acetamido-2-deoxy-D-glucopyranosyl

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• at all. Our study of the chemical behavior of 2H-azirines under Rh(II)-catalyzed decomposition of diazoketones was started with searching for optimal conditions for the catalytic reaction of 2,3-diphenyl-2H-azirine (1a) with 1-diazo-1-phenylpropan-2-one (2a), leading to oxazine 4a. The most

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

• Volodymyr V. Tkachenko,
• Elena A. Muravyova,
• Sergey M. Desenko,
• Oleg V. Shishkin,
• Svetlana V. Shishkina,
• Dmytro O. Sysoiev,
• Thomas J. J. Müller and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

• , salicylaldehyde (2) and acetoacetamide 3a in the presence of 5 mol % ytterbium triflate as a catalyst in ethanol under stirring at room temperature for 48 h led to the formation of the aforementioned dihydroisoxazolopyridine 5a in 69% yield. To our surprise the analogous catalytic reaction in ethyl alcohol under

• -component catalytic reaction with 5-amino-3-methylisoxazole (1) and salicylaldehyde (2) does not confirm this hypothesis since compound 6 was not observed in this case (Table 3, entries 23, 24). As one possible reason we assumed that the presence of an acidic phenol group – distinguishing the amide 3h from

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• the corresponding coupling product in relatively high yield (71%; Table 4, entry 5). As already observed in the hydroformylation experiments, HUGPHOS-1 generally gave slightly better results than the larger HUGPHOS-2, which points to a catalytic reaction taking place outside the cavity. It is

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• catalytic reaction, with no detectable aziridine product but remaining of the starting azides (Table 1, entries 1–3). It should be noted that azide 2c was previously shown to be a productive nitrene source for the catalytic aziridination reaction only at a high temperature of 80 °C [20]. Afterwards, we were

• reduction in reaction temperature (from 40 °C to 35 °C) and time (from 48 h to 36 h) was shown to have no obvious effect on both product yield and enantioselectivity (Table 1, entry 13). However, the catalytic reaction became significantly slower as the temperature further decreased. Under the optimized

• -subtituted styrene 1e (Table 2, entry 5), the catalytic reaction of the sterically demanding o-Br-substituted olefin 1k gave the desired aziridine in almost quantitative yield as well as high enantioselectivity (Table 2, entry 11). It is worthy to mention that the aryl halide units of these chiral aziridines

Cu-catalyzed trifluoromethylation of aryl iodides with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide

• Yuzo Nakamura,
• Motohiro Fujiu,
• Tatsuya Murase,
• Yoshimitsu Itoh,
• Hiroki Serizawa,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2013, 9, 2404–2409, doi:10.3762/bjoc.9.277

• trifluoromethyl iodide and Zn dust in DMPU. The catalytic reaction proceeded to provide moderate to high yields and a high selectivity of the trifluoromethylated product under mild reaction conditions. The advantage of this catalytic reaction is that additives such as metal fluoride (MF), which are indispensable

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• -based transformations are amongst the most attractive methods for the use in catalytic cycles due to the ease of radical generation, high functional group tolerance, and selectivity in C–C bond formation [3][4][5]. Recently, we have reported a novel catalytic reaction, a radical arylation of epoxides [6

• for the addition of 1 readily explains the excellent synthetic results with epoxides derived from aryl substituted anilines in the radical arylation of epoxides. The reaction of 3 is too slow to be useful in typical radical chain reactions. However, reactions under our catalytic reaction conditions [6

Palladium(II)-catalyzed Heck reaction of aryl halides and arylboronic acids with olefins under mild conditions

• Tanveer Mahamadali Shaikh and
• Fung-E Hong

Beilstein J. Org. Chem. 2013, 9, 1578–1588, doi:10.3762/bjoc.9.180

• , entry 4). Therefore, it is believed that NBS plays an important role in this catalytic reaction. Furthermore, we focused our attention to other solvents such as MeOH, CH2Cl2, CH3CN, Me2O, t-Bu2O, THF, DMSO and 1,4-dioxane, which resulted in low yields of arylated product. Subsequently, the reaction was

Coupling of C-nitro-NH-azoles with arylboronic acids. A route to N-aryl-C-nitroazoles

• Marta K. Kurpet,
• Aleksandra Dąbrowska,
• Małgorzata M. Jarosz,
• Katarzyna Kajewska-Kania,
• Nikodem Kuźnik and
• Jerzy W. Suwiński

Beilstein J. Org. Chem. 2013, 9, 1517–1525, doi:10.3762/bjoc.9.173

• acid. Most reports on the Chan–Lam coupling reaction underline the demand of air introduction into the reaction mixture to provide high yields of the products [22][24][36][37]. The plausible mechanism of this catalytic reaction was proposed by Evans [38] and described for N-nucleophiles by Collman [39

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• form another dichlorobis(anilino-ĸN)palladium(II) (3a–c) completing one cycle and liberating guanidines 5a–c as free products of this catalytic reaction with high yields and selectivities (see Scheme 4). In this mechanism the rate determining step will be the attack of dichlorobis(anilino-ĸN)palladium

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

• effectively formed, and the background reaction giving the racemic product proceeded. Additionally, the high Z-selectivity of product 9Ba indicates that the stereoselective iodine-atom transfer from isopropyl iodide to an intermediate radical proceeded effectively under these catalytic reaction conditions

Regio- and stereoselective carbometallation reactions of N-alkynylamides and sulfonamides

• Yury Minko,
• Morgane Pasco,
• Helena Chechik and
• Ilan Marek

Beilstein J. Org. Chem. 2013, 9, 526–532, doi:10.3762/bjoc.9.57

• species. To improve the chemical yield of this transformation, we considered the copper-catalyzed carbomagnesiation reaction. However, such catalytic reaction requires a transmetallation reaction of the intermediate vinylcopper into vinylmagnesium halide, and due to the intramolecular chelation, it is

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• pretreatment is necessary to activate the catalyst and a moisture-free medium is essential. Furthermore, a higher temperature (110 °C) and a longer reaction time (14 h) were also required for the catalytic reaction. Sartori et. al. suggested that the external surface of HSZ-360-Y zeolite was responsible for

• is directly related to its superior performance in the catalytic reaction. Iron probably has some role in lowering the activation energy of the reaction in synergy with the aluminium moiety present in Al-MCM-41. The short reaction time is probably due to the mesoporous structure of Fe-Al-MCM-41 (pore

• in the mesoporous matrix. Thus, the catalyst attained the desired site-isolation of active centers for enhanced activity in catalytic reaction. In fact, in order to investigate the role of mesoporous structure, we further performed the reaction with “degraded-Fe-Al-MCM-41” of which the mesoporous

Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

• Florian Boeck,
• Max Blazejak,
• Markus R. Anneser and
• Lukas Hintermann

Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186

• phosphorane structure (analogue to 5’) [43][44]. Under the conditions of the catalytic reaction, phosphonium (+37 ppm) was the only species of importance and thus represents the resting state of the catalytic reaction, which could be either 5 or 6. We did not observe a 31P NMR signal for n-Bu3P, or a signal

• for the phosphorane structure 5’, which is not favored in the highly polar solvent methanol [43]. Interestingly, we noted that quenching of the catalytic reaction mixtures with a cocatalytic amount of 1,2-dibromoethane prior to work-up had a favorable effect on product yield and purity: First, any of

Facile isomerization of silyl enol ethers catalyzed by triflic imide and its application to one-pot isomerization–(2 + 2) cycloaddition

• Kazato Inanaga,
• Yu Ogawa,
• Yuuki Nagamoto,
• Akihiro Daigaku,
• Hidetoshi Tokuyama,
• Yoshiji Takemoto and
• Kiyosei Takasu

Beilstein J. Org. Chem. 2012, 8, 658–661, doi:10.3762/bjoc.8.73

• , Japan 10.3762/bjoc.8.73 Abstract A triflic imide (Tf2NH) catalyzed isomerization of kinetically favourable silyl enol ethers into thermodynamically stable ones was developed. We also demonstrated a one-pot catalytic reaction consisting of (2 + 2) cycloaddition and isomerization. In the reaction

• procedure would be required. In this communication, we describe isomerization of silyl enol ethers by an organocatalyst under mild conditions and its application to a one-pot catalytic reaction involving isomerization of silyl enol ethers and (2 + 2) cycloaddition. Results and Discussion During our research

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• means of the reagent F–TEDA and chiral titanium Lewis acid catalysts of the TiCl2(TADDOLate) type [40][41][42]. The same catalytic reaction principle has also allowed the performance of asymmetric chlorinations and brominations of β-ketoesters [43][44][45]. After the initial report [40], many metal

• its stereoselectivity depending on reaction parameters and catalyst-ligand effects. We also present stereochemical correlations, to assign the absolute configuration of the fluorination products, and observations relevant to the mechanism of the catalytic reaction. A subsequent paper will cover the

• (Table 3, entry 15). At temperatures below 0 °C, the catalytic reaction was slow not only because of the thermal effect, but because of the limited solubility of F–TEDA. Additional temperature variation experiments were carried out with the more selective catalyst K2 and phenyl ester 6 as substrate