TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Bent Allenes or Di-1,3-betaines-An Answer Given on the Magnetic Criterion
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of bent allene 1, the corresponding C-extended 1,3-butadiene derivative 2, and a number of related compounds 3 -20 have been calculated using the gauge-independent atomic orbital perturbation method, employing the nucleus-independent chemical shift concept and visualized as isochemical shielding surfaces of various sizes and directions. Prior to that, both structures and C-13 chemical shifts were calculated and compared with available experimental bond lengths and delta(C-13)/ppm values (also, as a quality criterion for the computed structures). Bond lengths, the delta(C-13)/ppm, and the TSNMRS values are employed to qualify and quantify the electronic structure of the studied compounds in terms of dative or classical electron-sharing bonds.
Y1  - 2020
U6  - https://doi.org/10.1021/acs.jpca.0c01392
SN  - 1089-5639
SN  - 1520-5215
VL  - 124
IS  - 16
SP  - 3180
EP  - 3190
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Belasri, Khadija
A1  - Topal, Leila
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
A1  - Szatmari, Istvan
T1  - Synthesis and conformational analysis of naphthoxazine-fused phenanthrene derivatives
JF  - Molecules
N2  - The synthesis of new phenanthr[9,10-e][1,3]oxazines was achieved by the direct coupling of 9-phenanthrol with cyclic imines in the modified aza-Friedel-Crafts reaction followed by the ring closure of the resulting bifunctional aminophenanthrols with formaldehyde. Aminophenanthrol-type Mannich bases were synthesised and transformed to phenanthr[9,10-e][1,3]oxazines via [4 + 2] cycloaddition. Detailed NMR structural analyses of the new polyheterocycles as well as conformational studies including Density Functional Theory (DFT) modelling were performed. The relative stability of ortho-quinone methides (o-QMs) was calculated, the geometries obtained were compared with the experimentally determined NMR structures, and thereby, the regioselectivity of the reactions has been assigned.
KW  - modified Mannich reaction
KW  - cyclic imines
KW  - [4+2] cycloaddition
KW  - NMR
KW  - spectroscopy
KW  - conformational analysis
KW  - DFT calculations
Y1  - 2020
U6  - https://doi.org/10.3390/molecules25112524
SN  - 1420-3049
VL  - 25
IS  - 11
PB  - MDPI
CY  - Basel
ER  -