TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Werner, Peter
A1  - Koch, Andreas
T1  - Push-pull allenes-conjugation, (anti)aromaticity and quantification of the push-pull character
JF  - Tetrahedron
N2  - Structures, H-1/C-13 chemical shifts, and pi electron distribution/conjugation of an experimentally available and theoretically completed set of push-pull allenes Acc(2)C=C=CDon(2) (Acc=F, CHO, CF3, C  N; Don=t-Bu, OMe, OEt, SMe, SEt, NCH2R) have been computed at the OFT level of theory. Both orthogonal linear and orthogonal bent structures have been obtained. In the latter case the push-pull character could be quantified by the quotient method. The C-13 chemical shift of the central allene carbon atom C-2 and chemical shift differences Delta delta(C-1, C-2) and Delta delta(C-2, C-3) of allene carbon atoms proved to be a quantitative alternative. TSNMRS of ring-closed push-pull allenes have been computed in addition and were employed to identify polar, carbene-like and carbone-like canonical structures of these molecules.
KW  - Push-pull allenes
KW  - Push-pull character
KW  - C-13 NMR spectroscopy
KW  - Quotient method
KW  - TSNMRS
KW  - ICSS
KW  - Aromaticity
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.01.027
SN  - 0040-4020
VL  - 69
IS  - 11
SP  - 2436
EP  - 2445
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Rasovic, Aleksandar
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Markovic, Rade
T1  - Studies of the regioselective ring-opening closing mode of functionally different thiazolidine type enaminones - en route to the synthesis of trithiaazapentalene derivatives
JF  - Tetrahedron
N2  - Trithiaazapentalene derivatives were prepared by the reaction of 2-alkylidene-4-oxothiazolidines with Lawesson's reagent. They are classified as two structurally different trithiaazapentalene compounds that have different contributions of monocyclic 1,2-dithiole and 1,2,4-dithiazole structures and degrees of aromaticity of the bicyclic trithiaazapentalene system. The electron-donating ability of substituents at the C(5) position of the trithiaazapentalene system is recognized as the main cause for changes in pi-Celectron distribution. This is the first complete study of substituent effects on the structure of trithiapentalenes. (C) 2013 Elsevier Ltd. All rights reserved.
KW  - Trithiapentalene
KW  - 1,2-Dithiole
KW  - 1,2,4-Dithiazole
KW  - 4-Oxothiazolidine
KW  - Rearrangement to trithiaazapentalene
KW  - Push-pull character
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.10.088
SN  - 0040-4020
VL  - 69
IS  - 51
SP  - 10849
EP  - 10857
PB  - Elsevier
CY  - Oxford
ER  -