The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• of incorporating this scaffold into diverse organocatalysts. In 2008, Seidel’s group published a new example of an asymmetric addition of indoles to nitroalkenes, employing a novel catalyst design [24]. The authors envisioned that a protonated 2-pyridyl substituent could increase the acidity of the

Ruthenium indenylidene “1^st generation” olefin metathesis catalysts containing triisopropyl phosphite

• Stefano Guidone,
• Fady Nahra,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2015, 11, 1520–1527, doi:10.3762/bjoc.11.166

• ’-bis[2,4,6-(trimethyl)phenyl]imidazolidin-2-ylidene) afforded a Ru pre-catalyst displaying an unusual cis-geometry [25]. cis-Caz-1, which is more thermodynamically stable than its trans-isomer represents a breakthrough in catalyst-design for metathesis reactions of challenging hindered substrates

• the mixed NHC/phosphite cis-Caz-1 suggest the importance of synergistic effects involving phosphites, an inexpensive alternative to phosphines for Ru-based pre-catalysts, and the L-type ligands, a concept that can be used to incite further improvements in catalyst design. Experimental Synthesis and

Creating Complexity

• Donald Craig

Beilstein J. Org. Chem. 2013, 9, 1881–1882, doi:10.3762/bjoc.9.220

• searching for quicker, more efficient, more selective, less energy-intensive and more sustainable ways of creating complexity. The search for such improved methods creates additional complexity, whether they involve innovative catalyst design and synthesis, the streamlining of synthesis routes through the

Design and synthesis of a photoswitchable guanidine catalyst

• Philipp Viehmann and
• Stefan Hecht

Beilstein J. Org. Chem. 2012, 8, 1825–1830, doi:10.3762/bjoc.8.209

Asymmetric desymmetrization of meso-diols by C₂-symmetric chiral 4-pyrrolidinopyridines

• Hartmut Schedel,
• Keizo Kan,
• Yoshihiro Ueda,
• Kenji Mishiro,
• Keisuke Yoshida,
• Takumi Furuta and
• Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

• site because PPY has been known to be one of the most powerful catalysts for the acylation of alcohols [4][5][6][7]. The salient feature of our catalyst design is to introduce chiral elements far from the catalytically active pyridine nitrogen as shown in Figure 1 [8][9][10][11][12][13][14][15][16][17

C–H Functionalization

• Huw M. L. Davies

Beilstein J. Org. Chem. 2012, 8, 1552–1553, doi:10.3762/bjoc.8.176

• controlling elements of the various methods has to be obtained. This Thematic Series highlights some of the novel approaches that are applied to the field of C–H functionalization and I thank all the authors for their exciting contributions. The series covers topics that range from novel catalyst design, new

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• in THF at −78 °C gave again the racemic product in 78% yield. Hence, yield rather than ee value is influenced here by the reaction temperature. In order to explain the enantioselectivities observed, as well as to refine the catalyst design, or possibly get ideas that can be transferred to other

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

• Marcus Frings,
• Isabelle Thomé and
• Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

• centers in the catalyst backbone. Overall, promising results have been achieved, which shall be taken as stimulus for further investigations of structurally related sulfonimidoyl-containing thioureas. In that catalyst design, the aforementioned aspects related to structure, activity and stereoselectivity

Cation affinity numbers of Lewis bases

• Christoph Lindner,
• Raman Tandon,
• Boris Maryasin,
• Evgeny Larionov and
• Hendrik Zipse

Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163

• achieve with this catalyst design. In contrast, substantial re/si face differences have been obtained for Lewis bases 352 and 354, indicating that these compounds may be useful catalysts for stereoselective transformations. This property is already well established for quinine (356) and quinidine (357

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• rational catalyst design. Nevertheless, because of the commercial availability and high stability of the pre-catalysts as well as the simplicity of operation, this classical system is still widely used by chemists [20][21][22][23][24][25][26][27][28]. Schrock system Schrock-type catalysts are high

• hexafluoro-tert-butoxide, OCCH3(CF3)2, proved to be essential for creating active catalysts [74], indicating that successful catalyst design in this system relies on establishing a push-pull situation in a similar fashion present in Schrock–Hoveyda olefin metathesis catalysts (Scheme 4) [10] and also in an

• ]cycloaddition/cycloreversion mechanism (Scheme 1). Alkylidyne complexes 9 and 10. Alkyne metathesis based on the Katz mechanism. Reaction patterns of alkyne metathesis. Typical examples from traditional catalyst systems. Ligand synthesis and catalyst design. Catalysts synthesis using high- and low-oxidation

Catalysis: transition-state molecular recognition?

• Ian H. Williams

Beilstein J. Org. Chem. 2010, 6, 1026–1034, doi:10.3762/bjoc.6.117

• reduction in barrier height by means of differential stabilisation. The cases discussed below all exemplify TS molecular recognition and stabilisation relative to the reactant state. Catalyst design: preferential TS binding Methyl group transfer from an electrophile to a nucleophile by an SN2 mechanism is

• (= ΔERstabilise + ΔERcompress) < ΔETbind ( = ΔETstabilise + ΔETcompress) leading to net TS stabilisation. Later we proposed [16] a more realistic catalyst design for methyl transfer in the shape of inside-methylated [1.1.1]cryptand (Scheme 2). B3LYP/6-31G* calculations predicted the inter-bridgehead N…N distance

• enzyme-catalysed methyl transfer. Catalyst design for methyl transfer: (a) the reaction to be catalysed; (b) dipoles favourably aligned with the transition structure; (c) electrostatic potential plotted on the isodensity contour surface of the transition structure; (d) electrostatic potential (on

Control of asymmetric biaryl conformations with terpenol moieties: Syntheses, structures and energetics of new enantiopure C₂-symmetric diols

• Y. Alpagut,
• B. Goldfuss and
• J.-M. Neudörfl

Beilstein J. Org. Chem. 2008, 4, No. 25, doi:10.3762/bjoc.4.25

• ), (−)-verbenone (BIVOL) and (−)-carvone (BICOL and hydrogenated BIMEOL), are accessible via short, synthetic routes. All diols form intramolecular hydrogen bonds and hence can be employed as chelating ligands for catalyst design, as it demonstrated for the (−)-fenchone based BIFOL. The sense of asymmetry of the