TY  - CHAP
A1  - Burschka, Christian
A1  - Bringmann, Gerhard
A1  - Busse, Holger
A1  - Guessregen, Stefan
A1  - Schoener, Bernd
A1  - Zagst, Rainer
T1  - Structure and dynamics of free and metallated benzonaphthopyranones and -pyrans
N2  - First calculations of the structures of metal-free and complexed biaryl lactones and their confrrmation by X-ray crystaIlography, the search for the transition states of their heIimerization processes, and the spectroscopic determination of the heIimerization barriers of related cyclic ethers by DNMR are reported.
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46858
ER  - 
TY  - JOUR
A1  - Bringmann, Gerhard
A1  - Hartung, Thomas
A1  - Goebel, Lothar
A1  - Schupp, Olaf
A1  - Ewers, Christian L. J.
A1  - Schoener, Bernd
A1  - Zagst, Rainer
A1  - Peters, Karl
A1  - Von Schnering, Hans Georg
A1  - Burschka, Christian
T1  - Novel concepts in directed biaryl synthesis, IX:  Synthesis and structure of benzonaphthopyranones,  useful bridged model precursors for stereoselective biaryl syntheses
N2  - A practicable two-step procedure for the preparation of a series of lactone-type bridged biaryls 7 as favorable substrates for subsequent atropisomer-selective ring-opening reactions is described. Due to the efficiency of the coupling step, which tolerates even a telt·butyl group next to the biaryl axis and avoids problems of regioselectivity, a variety of differently substituted representatives is prepared. These cover a broad range of steric hindrance and thus molecular distortion. The structures are investigated mainly by NMR spectroscopy and X-ray diffraction, showing the lactones 7 to be helically distorted, depending on the size of the residues R.
KW  - Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46635
ER  - 
TY  - JOUR
A1  - Bringmann, Gerhard
A1  - Zagst, Rainer
A1  - Schöner, Bernd
A1  - Busse, Holger
A1  - Hemmerling, Martin
A1  - Burschka, Christian
T1  - Acetogenic Isoquinoline Alkaloids. XXIII. Structure of the Naphthyl Isoquinoline Alkaloid Dioncophylline A
N2  - No abstract available
KW  - Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31331
ER  - 
TY  - JOUR
A1  - Bringmann, Gerhard
A1  - Ortmann, Thomas
A1  - Zagst, Rainer
A1  - Schoener, Bernd
A1  - Assi, Laurent Ake
A1  - Burschka, Christian
T1  - +/- Dioncophyllacine A, a naphthylisoquinoline alkaloid with a 4-methoxy substituent from the leaves of Triphyophyllum peltatum
N2  - The isolation and structure elucidation of rac-dioncophyllacine A from the leaves of Triphyophyllun peltatum, is described. Unlike all other naphthylisoquinoline alkaloids, this fully dehydrogenated representative has an additional methoxy group at C-4, the position of which is deduced from NOE results. Dioncophyllacine A has a 7,1' site of the biaryl axis, as in dioncophylline A. Its constitution is confirmed by an X-ray structure analysis, which shows that the crystalline form of this new alkaloid is racemic.
KW  - Dioncophyllaceae
KW  - Triphyophyllum peltaturn
KW  - Dioncophyllaceae leaves
KW  - (± )-dioncophyllacine A
KW  - naphthylisoquinoline alkaloids
KW  - structure elucidation
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31873
ER  -