TY  - JOUR
A1  - Schwarz, Christopher
A1  - Scharf, Lennart T.
A1  - Scherpf, Thorsten
A1  - Weismann, Julia
A1  - Gessner, Viktoria H.
T1  - Isolation of the Metalated Ylides [Ph3P−C−CN]M (M=Li, Na, K): Influence of the Metal Ion on the Structure and Bonding Situation
JF  - Chemistry – A European Journal
N2  - The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph3P−C−CN]M (1-M; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium (1-Na) and potassium (1-K) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η2-coordination mode to the two central carbon atoms. The formation of the yldiide was accompanied by structural changes leading to shorter C−C and longer C−N bonds. This could be attributed to the delocalization of the free electron pairs at the carbon atom into the antibonding orbitals of the CN moiety, which was confirmed by IR spectroscopy and computational studies. Detailed density functional theory calculations show that the changes in the structure and the bonding situation were most pronounced in the lithium compounds due to the higher covalency.
KW  - alkali metals
KW  - bond theory
KW  - lithium
KW  - structure elucidation
KW  - solid-state structures
KW  - ylides
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-235445
VL  - 25
ER  - 
TY  - JOUR
A1  - Hartung, Andreas
A1  - Seufert, Florian
A1  - Berges, Carsten
A1  - Gessner, Viktoria H.
A1  - Holzgrabe, Ulrike
T1  - One-Pot Ugi/Aza-Michael Synthesis of Highly Substituted 2,5-Diketopiperazines with Anti-Proliferative Properties
JF  - Molecules
N2  - The well-known Ugi reaction of aldehydes with amines, carboxylic acids and isocyanides leads to the formation of acyclic alpha-acylaminocarboxamides. Replacement of the carboxylic acid derivatives with beta-acyl substituted acrylic acids gives access to highly substituted 2,5-diketopiperazines in one single reaction-step without additives or complex reaction procedures. The obtained diketopiperazines show anti-proliferative effects on activated T cells and represent therefore potential candidates for targeting unwanted T cell-mediated immune responses.
KW  - multicomponent Ugi-type reaction
KW  - intramolecular Michael addition
KW  - strategy
KW  - derivates
KW  - diketopiperazines
KW  - chemistry
KW  - T cell
KW  - 2,5-diketopiperazines
KW  - anti-proliferative effects
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130423
VL  - 17
IS  - 12
ER  -