Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues

• Aleksandra Jankowiak,
• Piotr Kaszynski,
• William R. Tilford,
• Kiminori Ohta,
• Adam Januszko,
• Takashi Nagamine and
• Yasuyuki Endo

Beilstein J. Org. Chem. 2009, 5, No. 83, doi:10.3762/bjoc.5.83

• fluorination [18][19] on mesophase stability, and also the effectiveness of shielding of a lateral substituent [8][16][20] and chirality transfer phenomena [17]. Results of these studies are important for the design of new materials and optimizing of their properties for applications. During our investigation

Chiral amplification in a cyanobiphenyl nematic liquid crystal doped with helicene-like derivatives

• Alberta Ferrarini,
• Silvia Pieraccini,
• Stefano Masiero and
• Gian Piero Spada

Beilstein J. Org. Chem. 2009, 5, No. 50, doi:10.3762/bjoc.5.50

• good solubility in the nematic host and high helical twisting power. Understanding of the mechanism behind chirality transfer from solute molecules to host nematic phases is essential for designing LC-based chiral devices; our and other research groups have investigated this issue (for a selection of

• lowest measured HTP. This is a confirmation of the fact that bulky substituents, though lacking centres of chirality (or other stereogenic elements), can strongly affect the molecule-to-phase chirality transfer. The data in Table 1 also show that, unlike derivatives 1–4, the [4]helicene quinones 6–8 have

Progress in liquid crystal chemistry

• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 48, doi:10.3762/bjoc.5.48

• smectic phases, nematic phase engineering by using V-shaped molecules, saddle-shaped columnar systems displaying anomalous odd-even effects, theoretical studies on the origin of chirality transfer in liquid crystalline host-guest systems, liquid crystalline carboranes and dyes and discotic phenanthrene

The role of an aromatic group in remote chiral induction during conjugate addition of α-sulfonylallylic carbanions to ethyl crotonate

• Shlomo Levinger,
• Ranjeet Nair and
• Alfred Hassner

Beilstein J. Org. Chem. 2008, 4, No. 32, doi:10.3762/bjoc.4.32

• increase in diastereoselectivity for the more electron deficient nitro derivative 1c. The most remarkable case of remote chirality transfer (over 99% dr), was observed for the 9-anthryl case 1h, which showed a rate enhancement as well [15][16]. In order to determine whether an unusual steric effect may

Conformational rigidity of silicon- stereogenic silanes in asymmetric catalysis: A comparative study

• Sebastian Rendler and
• Martin Oestreich

Beilstein J. Org. Chem. 2007, 3, No. 9, doi:10.1186/1860-5397-3-9

• metal-catalyzed asymmetric transformations as exemplified by (1) the hydrosilylation of alkenes constituting a chirality transfer from silicon to carbon and (2) the kinetic resolution of racemic mixtures of alcohols by dehydrogenative silicon-oxygen coupling. In this investigation, a cyclic and a

• inducing excellent chirality transfer (ct) in a palladium-catalyzed intermolecular carbon-silicon bond formation yet silicon incorporated into a cyclic framework is required in the copper-catalyzed silicon-oxygen bond forming reaction. Findings Within the last decade, several asymmetric transformations

• investigations directed towards the mechanistic elucidation of the origin of the chirality transfer in a palladium-catalyzed hydrosilylation, [10] we had to perform an extensive screening of silicon-stereogenic tertiary silanes. On that occasion, we became aware that a similar level of stereoselection was

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• , chirality transfer was carried out using chiral Lewis acid catalysts. However, these are often expensive, toxic, and not easily recycled. Up until this point, no chiral solvent is reported to have been used in this transformation. Therefore, when researching chiral ionic liquids (ILs), we had two objectives

• in mind: to promote 'green reaction media' and most importantly to provide a highly efficient chirality transfer due to the high degree of organization of the chiral ionic liquids. Chiral solvents are reported to have been already used as a sole inducer of enantiomeric excess in organic reactions

• a 'green method' for the chirality transfer in the aza-Diels-Alder reaction, we proceeded to elaborate the IL structure effect. To that end, a series of different alkyl chain lengths were tested on this model reaction (Table 2). Surprisingly, contrary to results obtained in the asymmetric Baylis