Asymmetric total synthesis of smyrindiol employing an organocatalytic aldol key step

• Dieter Enders,
• Jeanne Fronert,
• Tom Bisschops and
• Florian Boeck

Beilstein J. Org. Chem. 2012, 8, 1112–1117, doi:10.3762/bjoc.8.123

• reaction; asymmetric synthesis; organocatalysis; proline; smyrindiol; Introduction Furocoumarins are a group of compounds that are structurally derived from psoralen or angelicin (Figure 1) [1]. Naturally occurring furocoumarins are mainly found in plants of the Apiaceae and Rutaceae families [2] and are

• chromatograms. Acknowledgements This work was supported by the Deutsche Forschungsgemeinschaft (SPP 1179 “Organocatalysis”). We thank the former Degussa AG and the BASF SE for the donation of chemicals.

Chiral multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita–Baylis–Hillman carbonates with maleimides

• Hong-Ping Deng,
• De Wang,
• Yin Wei and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 1098–1104, doi:10.3762/bjoc.8.121

• previous literature. Keywords: asymmetric [3 + 2] annulation; maleimides; Morita–Baylis–Hillman carbonates; multifunctional thiourea-phosphine; organocatalysis; Introduction Highly functionalized cyclopentene derivatives are important subunits in a variety of biologically active molecules and have

Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

• Saet Byeol Woo and
• Dae Young Kim

Beilstein J. Org. Chem. 2012, 8, 699–704, doi:10.3762/bjoc.8.78

• organocatalysts is described. This reaction afforded the chiral functionalized naphthoquinones in high yields (81–95%) and excellent enantioselectivities (91–98% ee) under low catalyst loading (1 mol %). Keywords: asymmetric catalysis; Michael addition; 1,4-naphthoquinones; nitroalkenes; organocatalysis

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

• sequence, Tf2NH catalyzes both of the reactions. Keywords: isomerization; one-pot reaction; organocatalysis; silyl enol ethers; triflic imide; Introduction Silyl enol ethers, which are isolable equivalents of metal enolates, are useful and important intermediates in synthetic chemistry [1][2][3]. They

Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• substituted piperidines. Keywords: cascade; imine; Michael addition; nitro-Mannich; organocatalysis; piperidine alkaloids; Introduction The piperidine ring is a common motif found in many biologically active natural products and drugs. The structures of these compounds range from the architecturally complex

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis

• Rob De Vreese and
• Matthias D’hooghe

Beilstein J. Org. Chem. 2012, 8, 398–402, doi:10.3762/bjoc.8.43

• toward the synthesis of different heterocycles. Nonetheless, enantioselective control of homoenolates remained an important issue to be addressed, and this problem was tackled very recently by the group of T. Rovis [23]. Their important contribution to the field of organocatalysis originated from the

Binding of group 15 and group 16 oxides by a concave host containing an isophthalamide unit

• Jens Eckelmann,
• Vittorio Saggiomo,
• Svenja Fischmann and
• Ulrich Lüning

Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2

• to the steric bulk of the guests. These initial experiments now open the way for the synthesis of new modified concave hosts based on isophthalamide units with improved binding selectivity and/or for organocatalysis [21]. Concave host 1 can also be applied as a carrier in transport experiments. When

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

• Xacobe C. Cambeiro,
• Rafael Martín-Rapún,
• Pedro O. Miranda,
• Sonia Sayalero,
• Esther Alza,
• Patricia Llanes and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

• ]. With this methodology an α-aminoxyketone was obtained that could be readily transformed into the corresponding α-hydroxyketone in the presence of catalytic amounts of CuSO4·5H2O in methanol. This strategy was soon extrapolated to the field of organocatalysis, leading in 2003 [13] to the first

• organocatalyzed α-aminoxylation of aldehydes and ketones experienced in the last few years has transformed it into a powerful, reliable and environmentally friendly method for the synthesis of α-hydroxyaldehydes and ketones [32][33][34]. Despite its extreme simplicity and very high enantiocontrol, organocatalysis

Multicomponent synthesis of artificial nucleases and their RNase and DNase activity

• Anton V. Gulevich,
• Lyudmila S. Koroleva,
• Olga V. Morozova,
• Valentina N. Bakhvalova,
• Vladimir N. Silnikov and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2011, 7, 1135–1140, doi:10.3762/bjoc.7.131

• activity of the new compounds towards single-stranded RNA and double-stranded circular DNA. Keywords: DNA; isocyanide; multicomponent reaction; organocatalysis; peptidomimetic; RNA; Introduction RNA cleavage can serve as a molecular tool for biological research [1], as well as for development of

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• in organocatalysis has been demonstrated in several examples [40][41][42][43][44]. Herein, we report the synthesis of ureido- and thioureido-substituted dibenzobarrelene derivatives 1e–i, along with first studies of their photochemical properties in the absence and in the presence of anions. Results

• systematically to influence the photochemical properties of a substrate, although such supramolecular receptor–anion interactions have been used in the organocatalysis of ground-state reactions [40][41][42][43][44]. It should be noted that the supramolecular interactions between anions and ureido- or thioureido

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

• highly enantioselective electrophilic trifluoromethylation of aldehydes has only very recently been reported by MacMillan by using a combination of organocatalysis with Togni’s reagent 37 [39]. This report appeared only just after a photolytic approach, also reported by MacMillan, that employs CF3

Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.0^2,6]decane skeleton

• Matthias Breuning,
• Tobias Häuser,
• Christian Mehler,
• Christian Däschlein,
• Carsten Strohmann,
• Andreas Oechsner and
• Holger Braunschweig

Beilstein J. Org. Chem. 2009, 5, No. 81, doi:10.3762/bjoc.5.81

• β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis. Keywords: amino acid; enantioselective synthesis; norbornane; polycyclic compounds; pyrrolidine; Introduction Unnatural amino acids with a rigid bowl-shaped backbone have received

• ][8] are embedded in peptidomimetics (Figure 1). Enantioselective organocatalysis [9][10][11][12][13][14][15][16][17] is another field of application for conformationally rigid amino acid derivatives. In this context, focus was also put on derivatives in which the activating acidic group is anchored

• are promising candidates as ß-turn-inducing building blocks in peptidomimetics and as chiral auxiliaries in organocatalysis. The conformationally rigid amino acid derivatives 1–3 (β-turn-inducing building blocks) and 4–6 (successful organocatalysts). The targeted tricyclic amino acid derivatives 7 and

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

• catalytic efficiency. Keywords: asymmetric; catalysis; enzymes; organocatalysis; transition metal complexes; Introduction The preferential formation of one enantiomer of a molecule via asymmetric catalysis remains one of the most challenging and exciting areas of academic and industrial research in

• chemistry [1]. Enormous progress has been made in recent years, most notably in homogenous transition metal catalysis, organocatalysis and enzyme-catalysed reactions. It is therefore surprising that there is no generally accepted measure for the effectiveness of a catalytic reaction. That is to say when we

C₂-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels- Alder reaction of anthrones

• Deniz Akalay,
• Gerd Dürner,
• Jan W. Bats and
• Michael W. Göbel

Beilstein J. Org. Chem. 2008, 4, No. 28, doi:10.3762/bjoc.4.28

• a cycloaddition step stereoselectively controlled by the chiral ion pair. Keywords: Asymmetric Catalysis; Bisamidines; Brønsted base; Diels-Alder reaction; Organocatalysis; Introduction The cycloadditions of anthrones 1 and N-substituted maleimides 2 are prominent examples of asymmetric catalysis

• compound 3m Acknowledgements Financial support provided by the DFG (Priority Program “Organocatalysis” SPP1179) and by the FAZIT STIFTUNG is gratefully acknowledged.

The first organocatalytic carbonyl- ene reaction: isomerisation- free C-C bond formations catalysed by H-bonding thio- ureas

• Matthew L. Clarke,
• Charlotte E. S. Jones and
• Marcia B. France

Beilstein J. Org. Chem. 2007, 3, No. 24, doi:10.1186/1860-5397-3-24

• organocatalytic carbonyl ene reaction and shown that some asymmetric induction is possible if a chiral thiourea catalyst is employed. However, turnover frequency, enantioselectivity and substrate scope are all very modest, suggesting that for intermolecular ene reactions, organocatalysis may not be a promising

Stereoselective α-fluoroamide and α-fluoro- γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement

• Kenny Tenza,
• Julian S. Northen,
• David O'Hagan and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2005, 1, No. 13, doi:10.1186/1860-5397-1-13

• reagents, either using asymmetric enolates, [3][4] asymmetric fluorinating reagents[5][6] or asymmetric Lewis acids.[7][8][9] Most recently organocatalysis mediated asymmetric fluorinations have been explored[10] and this has resulted in the efficient preparation of α-fluoroaldehydes in high enantiomeric