Spectroscopy and photophysics of bifunctional proton donor-acceptor indole derivatives.

We report spectroscopic and photophysical studies of a series of selected indole derivatives in solutions and under supersonic jet isolation conditions. All the compounds can assume two rotameric forms, syn and anti. The bifunctional molecules containing both the hydrogen bond donor (indole NH group) and acceptor centers (oxygen, nitrogen, or sulfur atoms) located in separate moieties covalently linked by a single bond are compared with the compound that does not have any acceptor center, 2-(1H-pyrrol-2'-yl)-1H-indole.

Tosyl esters of cinchonidine and cinchonine alkaloids: the structure-reactivity relationship in the hydrolysis to 9-epibases.

In the crystal structures of the diastereoisomers of O-tosylcinchonidine [(9R)-cinchon-9-yl 4-methylbenzenesulfonate], (I), and O-tosylcinchonine [(9S)-cinchon-9-yl 4-methylbenzenesulfonate], (II), both C(26)H(28)N(2)O(3)S, both molecules are in an anti-closed conformation and, in each case, the position of the aryl ring of the tosylate system is influenced by an intramolecular C-H···O hydrogen bond. The molecular packing in (I) is influenced by weak intermolecular C-H···O and C-H···π interactions. The crystal structure of (II) features C-H···π interactions and van der Waals forces only.

5,6,7,8-Tetra-hydro-quinolin-8-one.

In the quinoline fused-ring system of the title compound, C(9)H(9)NO, the pyridine ring is planar to within 0.011 (3) Å, while the partially saturated cyclo-hexene ring adopts a sofa conformation with an asymmetry parameter ΔC(s)(C6) = 1.5 (4)°.

5,6,7,8-Tetra-hydro-quinoline 1-oxide hemihydrate.

In the title compound, C(9)H(11)NO·0.5H(2)O, the asymmetric unit contains two similar mol-ecules of 5,6,7,8-tetra-hydro-quinoline 1-oxide and one water mol-ecule. The water mol-ecule links the two O atoms of both independent N-oxides into dimers via O-H⋯O hydrogen bonds, forming a three-dimensional network along [101], which is additionally stabilized by weak C-H⋯O inter-molecular inter-actions.

Metal complexes of cinchonine as chiral building blocks: a strategy for the construction of nanotubular architectures and helical coordination polymers.

The first chiral bipyridyl-type metalloligands based on aluminum derivatives of cinchonine (CN-H) were synthesized and characterized by single-crystal X-ray diffraction studies. These bischelate complexes, (CN)(2)AlX [X = Cl (1a), Me (1b)] were found to be effective building blocks for the preparation of novel helical nanotubular architectures as well as chiral bimetallic coordination polymers, as demonstrated by the rational synthesis of a helical structure formed by 1a and ZnCl(2). The applied methodology stands as an exemplary strategy for the rational synthesis of chiral metal-organic frameworks through self-organization driven by nonbonding interactions or coordination, which could potentially find applications in enantioselective separations and catalysis.

A new approach to difficult Fischer synthesis: the use of zinc chloride catalyst in triethylene glycol under controlled microwave irradiation.

[reaction: see text]. Application of triethylene glycol with catalytic quantity of zinc chloride (ZnCl2/TEG) is described as a new and efficient reaction medium for a difficult Fischer synthesis, leading to sensitive indoles. Transformation of the 3-acetyl-1-methylthiocycloalka[c]pyridine phenylhydrazones and p-methoxyphenylhydrazones into the 2-(2-pyridyl)indoles and 5-methoxy-2-(2-pyridyl)indoles, which are the synthons in our total synthesis of the sempervirine-type alkaloids, is carried out under controlled microwave irradiation in dry zinc chloride solution (0.