D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• nitrile is slower compared to the unstabilized 9b. The Stoltz and co-workers reported the preparation of a series of PHOX ligands using Buchwald’s copper-catalyzed C–P bond construction [48][49]. This reaction allows the Ullmann coupling of aryl halides with secondary phosphines to afford tertiary

• phosphines. We chose Stoltz’s protocol to introduce the diphenylphosphine moiety to our β-configurated bromoaryloxazolines 10a–i as well as to oxazoline 11i due to the fact that the peracetylated sugar could be obtained as an α-anomer in relatively high yield. The reaction afforded the spiro-fused PHOX

• phosphines can be used as nucleophiles for deacetylation reactions [50][51]. We suppose that the lower yields of 5f–i and 14a can be explained by partial or full deacylation of the protective groups. This explanation is also in good accordance with the fact that the yield of the ester protected PHOX ligand

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

• and Discussion We initiated our studies by probing various reaction conditions for the envisioned C–H amidation of ferrocene 1a (Table 1). Among a variety of ligands, N-heterocyclic carbenes and phosphines provided unsatisfactory results (Table 1, entries 1–3), while the product 3aa was formed when

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

• of several phosphines and pyridine-type ligands, the latter ligands were found to be the most effective for use in the coupling reaction. Consequently, we found that iminopyridine L3 was the best choice of ligand, and when used, it resulted in the three-component product 4a being obtained in 69

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

• enantiomerically pure (S)-(2-diphenylthiophosphinoferrocenyl)methanol. Deprotection of the thiophosphine unit(s) by tris(dimethylamino)phosphine gave chiral calixarene phosphines 27–29 bearing ferrocenyl substituents on the lower rim in high yields. Calixarene-derived mono(ferrocenylphosphine) ligands 27 and 28

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• temperature. While monodentate phosphines such as PPh3 and PCy3 were entirely ineffective (Table 1, entries 1 and 2), common bulky NHC precursors such as 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (IMes·HCl) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (IPr·HCl) promoted the coupling

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• are utilised. The employment of a variety of different ligands such as phosphines, amines and carbenes allows precise tuning of the properties of homogeneous Pd catalysts, which led to significant improvements in turn over number (TON), reaction rates, enantioselectivity as well as catalyst robustness

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• ) groups in good-to-high yields and enantioselectivities. Axial backbones and substituents on phosphorus atoms of chiral phosphine ligands critically influence the enantioselectivity. Moreover, the methylation of simple perfluoroalkylated ketones is found to be facilitated by only chiral phosphines without

• product (25% yield, 0% ee). Interestingly, the use of only BINAP without CuTC led to higher reactivity and enantioselectivity (54% yield, 8% ee), while BTFM-Garphos decreased the reactivity (7% yield, 8% ee). After screening of phosphines, DTB-MeO-BIPHEP was found to smoothly catalyze the asymmetric

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• anticancer drugs, antioxidants, or functional probes into the mitochondria [5][6][7][8]. Review 1. Synthesis of vinylphosphonium salts 1.1. Alkylation of phosphines with alkyl halides One of the most common methods for the preparation of vinylphosphonium salts 1 is the quaternization of vinylphosphines with

• Wehman (Scheme 4) [10]. Vinylphosphonium salts can also be prepared by alkylation of phosphines (usually triphenylphosphine) with allyl halide derivatives and isomerization of allylphosphonium salts 4 thus obtained under the influence of bases such as triethylamine or sodium carbonate (Scheme 5) [11][12

• closure and the formation of dialkyl 2-(alkylamino)-5-aryl-3,4-furanedicarboxylate 124 in a yield of 69–88% (Scheme 69). The reaction was carried out for several hours at room temperature in anhydrous CH2Cl2 [81]. Recently, an interesting one-pot condensation of acetylenedicarboxylates with phosphines and

Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• Beller and co-workers (Scheme 1, reaction 2) [33]. The use of NHCs proved to be the key, since the more accessible monodentated phosphorus ligands such as triphenyl (Ph3P) or tricyclohexyl (Cy3P) phosphines showed a significant lower efficiency and different selectivity with the same palladium source Pd

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• Suzuki–Miyaura coupling between 5-(triazinyloxy)oxazole 3aa and phenylboronic acid (4a, Table 2). As expected, the desired trisubstituted oxazole 5aaa was obtained in 21% yield (Table 2, entry 1). The use of different bidentate (dppp) or monodentate (PCy3) phosphines as ligands for the Ni catalyst

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• strategies with chiral transition metals [27][28][29][30][31][32][33], organocatalysts such as secondary amines [34][35][36], nucleophilic phosphines [26][37][38][39][40][41][42][43][44], tertiary amines [45], N-heterocyclic carbenes (NHCs) [46][47][48], and cinchona alkaloid derivatives [25][28][49][50

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• simply mixing at room temperature Au3+ salts and thio-glucoside as reducing and stabilizing agents, without the addition of NaBH4 [19]. The two-step synthetic procedure consists in the initial synthesis of AuNPs stabilized by temporary compounds (i.e., citrates, amines or phosphines), followed by the

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines. Keywords: aza-Wittig reactions; catalysis; phosphines; phosphine oxides; reduction; silanes; Wittig reactions; Introduction The Wittig reaction is a venerable transformation for

• impediment to the development of phosphine-catalyzed Wittig reactions was the stability of phosphine oxides and the harsh reaction conditions generally required to reduce them to the corresponding phosphines were thought to be incompatible with various necessary reactants and reagents, and the desired

• reaction (Scheme 8) [22]. This reaction involved the intramolecular cyclization of 27 to form 28. A variety of phosphines were examined as the catalyst, and (S,S)-29 ((S,S)-Me-DuPhos, 0.1 equivalent) was found to provide the best combination of reactivity and stereoselectivity (39% yield, 62% ee). In these

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• dissolves in solutions of o-quinones [9][10][11]. This process is greatly accelerated by the presence of auxiliary ligands, such as phosphines or pyridines. But the oxidation of copper metal with a reduced protonated quinone, which is (1)H2 in fact, was observed for the first time. This process leads to the

• reduction process of copper with (1)H2. The EPR signal corresponding to (1·−)H2 could be observed only if a chelating diphosphine was used as an auxiliary ligand in the reaction of copper with (1)H2. Most likely, phosphines such as dppe, dppb or dppfc provide better stability for the copper(I) ion in

• solution due to chelation. It should be mentioned, that the reduction of (1)H2 with copper metal proceeds also in the presence of non-bridging phosphines, such as PPh3, but the radical anion species (1·−)H2 is stable only in the presence of a large counterion such as [Cu(dppe)2]+. The signal of the solvent

Enantioconvergent catalysis

• Justin T. Mohr,
• Jared T. Moore and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192

• type I enantioconvergent catalysis was reported by Glueck for the preparation of enantioenriched P-chiral phosphines (Scheme 2) [17]. In this process, enantiopure Pd complex (R,R)-4 reacts with racemic phosphine 3 to form phosphido complexes 5 and 6. Although the rate of configurational inversion of

• . Enantioconvergent synthesis of phosphines governed by Curtin–Hammett/Winstein–Holness kinetics (TMS = trimethylsilyl, Is = 2,4,6-triisopropylphenyl). Stoltz’ stereoablative oxindole functionalization. Fu’s type II enantioconvergent Cu-catalyzed photoredox reaction. Stereoablative enantioconvergent allylation and

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• protonation or quaternization of neutral precursors (imidazoles, amines, phosphines, pyridine or sulfides) with Brønsted acids or haloalkanes/dialkylsulfates, respectively. In the next step, a variety of ionic liquids are obtainable by anion exchange, either through direct treatments with Lewis acids or by

• diols can be carried out in the presence of basic (e.g., tertiary phosphines and amines, alkali metal hydroxides, alkoxides, halides, carbonates, alkali metal exchanged faujasites and hydrotalcites) or acidic catalysts or co-catalysts, and under thermal (non-catalytic) conditions. All applicable

• phosphines and amines by dimethyl carbonate (Q = N, P). Bottom: anion metathesis of methyl carbonate onium salts. Synthesis of the acid polymeric IL. EGDMA: ethylene glycol dimethacrylate. The transesterification of sec-butyl acetate with MeOH catalyzed by some acidic imidazolium ILs. Top: phosgenation of

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• of the CO ligand by phosphines in [M(CO)2Cl(NHC)] complexes (M = Rh, Ir) or even by DMSO [60][61][62] occurs at the trans-CO ligand. In some cases, loss of CO upon formation of dimers can be observed for rhodium NHC complexes [63][64][65]. Ligand exchange in square planar Rh(I) carbonyl complexes was

A T-shape diphosphinoborane palladium(0) complex

• Patrick Steinhoff and
• Michael E. Tauchert

Beilstein J. Org. Chem. 2016, 12, 1573–1576, doi:10.3762/bjoc.12.152

• complexes only few examples featuring a η1-type Pd→B interaction have been reported [6][7]. However, these complexes require phosphines or pyridines as a stabilizing co-ligand, which can act as an inhibitor in catalytic transformations [7]. Similarly, monometallic 14 VE palladium complexes featuring a

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• haptotropic rearrangement of 48 to 53. Notice that passage through the η2 intermediate causes the phosphines to become equivalent. Benn and co-workers [74] in fact observe phosphine equivalence with a barrier of approximately 13 kcal/mol for the naphthalene–Ni(PR3)2 compounds. Our calculations put 54 to be

• found on the potential energy surface of C8F8–Pt(dpe). For clarity the groups around the phosphines have been removed. The relative energies for this compound, as well as COT–Pt(dpe) are given below each structure. The two important bonding interactions for transition state 31 are drawn in 33 and 34

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

• reported the hydrophosphination of methacrylonitirle 174 catalyzed by nickel(II)/(R,R)-Pigiphos complex 171 (Scheme 41) [71]. The reaction proceeded in good yield for alkyl phosphines (71–97% yield) and with higher enantioselectivity for the more sterically encumbered alkyl groups (R = Ad, 97:3 er). Togni

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• from the secondary phosphines by deprotonation with KH in refluxing THF. The NeoPHOX ligands, which were obtained by this route in high overall yield, proved to be air and moisture stable and could be obtained in analytically pure form by simple filtration through silica gel [19]. Complexation with [Ir

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• , entry 5). In general, untethered, exogenous sulfoxides are poorer ligands to ruthenium than phosphines or phosphites. As the reaction temperature is lowered to 40 °C, however, one begins to see a significant decrease in reaction rate and conversion (Table 1, entry 6). The enantioselectivity of the

• phosphines, biaryl sulfoxides, or monoaryl monoalkyl sulfoxides. After 1.5 hours, (S)-methyl p-tolyl sulfoxide also showed no conversion (Table 4, entry 5). Since subtle changes in the structure of the enyne substrate could have a significant impact on enantioselectivity, variations of the substituent on

Enantioselective [3 + 2] annulation of α-substituted allenoates with β,γ-unsaturated N-sulfonylimines catalyzed by a bifunctional dipeptide phosphine

• Huanzhen Ni,
• Weijun Yao and
• Yixin Lu

Beilstein J. Org. Chem. 2016, 12, 343–348, doi:10.3762/bjoc.12.37

• -sulfonylimines proceeded in an unexpected [3 + 2] annulation mode to afford a cyclopentene ring with an all-carbon quaternary center (Scheme 1) [48]. In recent years our group has developed a family of amino acid-derived bifunctional phosphines and has intensively investigated related asymmetric transformations

• allenoate 1a and β,γ-unsaturated N-sulfonylimine 2a as a model reaction and evaluated a number of amino acid based bifunctional phosphines as catalyst. As shown in Table 1, simple L-valine-derived phosphines 3a–c were found to be effective in promoting the reaction, and products were obtained in moderate to

• phosphine catalyst furnishes the final [3 + 2] annulation product 5. Conclusion In conclusion, we have described the first enantioselective [3 + 2] cycloaddition of α-substituted allenoates with β,γ-unsaturated N-sulfonylimines, catalyzed by amino acid-derived bifunctional phosphines. The [3 + 2] annulation

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• commercial impacts during the last decades, phosphates, phosphonates, phosphinates, or phosphines being prominent in several fields. As an example, drugs bearing an organophosphorus moiety hold a significant place in chemotherapy for the treatment of various diseases. Nevertheless, the high polarity of these

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• -catalyzed reactions, phosphines, N-heterocyclic carbenes, pyridines and salen ligands have been applied as ligands for controlling the stability of catalysts, and chemo-, regio- and enantioselectivities of the reactions [31][32][33][34][35][36]. Recent advances in the gold-catalyzed reactions are