Conformational analysis and intramolecular interactions in monosubstituted phenylboranes and phenylboronic acids

• Josué M. Silla,
• Rodrigo A. Cormanich,
• Roberto Rittner and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2013, 9, 1127–1134, doi:10.3762/bjoc.9.125

• coplanar to the aromatic ring) is governed by the strong πCC→pB interaction (Table 5). As in the case of 1, a hypothetical nX→pB interaction for the halogen derivatives 3–5 is not sufficiently strong to stabilize the conformation with the H–B–H moiety orthogonal to the benzene ring, confirming the weak

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• , Wuhan 430070, China 10.3762/bjoc.9.30 Abstract The hydrochloride of the racemic amino acid (2-(7-hydroxycoumarin-4-yl)ethyl)glycine, which can serve as a fluorescent probe in proteins, and two halogen derivatives of it, were synthesized by using a new synthetic protocol in five steps. It is less costly

• and relatively easy to prepare this kind of fluorescent amino acid with the new synthetic method. Furthermore, it can be applied to synthesize other derivatives of the coumarin amino acid with some specific properties. Keywords: coumarin; fluorescent probe; halogen derivatives; non-natural amino acid

• amino acid, we designed a new synthetic protocol for compound 1a and two further halogen derivatives (1b and 1c). This new approach avoids some of the problems discussed above. It has a good overall yield and only requires reagents that are relatively cheap or easy to prepare. Compounds 1b and 1c have

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

• Sonja Findeisen-Tandel,
• Wolfgang Weissflog,
• Ute Baumeister,
• Gerhard Pelzl,
• H. N. Shreenivasa Murthy and
• Channabasaveshwar V. Yelamaggad

Beilstein J. Org. Chem. 2012, 8, 129–154, doi:10.3762/bjoc.8.15

• , for example from nematic to SmCP, nematic to USmCP, BX to SmCP, and SmCP to columnar. The influence of one halogen atom attached at the outer phenyl rings was investigated in several nonsymmetric molecules. The mono-halogen derivatives of three series are isomeric to each other (OH 1b–c, OH 2e–g, OH

• clearing temperatures by only 2–6 K. Looking at the compounds OH 5e–g, which have two halogen atoms, i.e., one halogen atom at each leg, the lowering of the clearing points found for mono-halogen derivatives is approximately doubled. Nevertheless, the effect of lateral halogen atoms on the mesophase