Refine
Has Fulltext
- yes (5)
Is part of the Bibliography
- yes (5)
Document Type
- Journal article (5)
Language
- English (5)
Keywords
- structure elucidation (2)
- ylides (2)
- 2,5-diketopiperazines (1)
- R factor = 0.025 (1)
- T = 173 K (1)
- T cell (1)
- alkali metals (1)
- anti-proliferative effects (1)
- bond theory (1)
- carbanion (1)
Institute
EU-Project number / Contract (GA) number
- 677749 (1)
The title compound, \(C_{21}H_{21}O_2PS_2\), was obtained from the corresponding dilithio methandiide by treatment with iodo-methane. The bond lengths and angles deviate considerably from those in the dimetallated compound. These differences are most pronounced in the PCS backbone. While the title compound features C-P and C-S distances of 1.9082(17) and 1.8348(17)Å, respectively, the dianion showed \(C-P_{av}\) distances shortened by 11% [1.710(4)Å] and C-S distances shortened by 12% [1.614(3)Å]. Additionally, the P-C-S angle experiences a contraction by methyl-ation of the dianion from 121.4(2) to 111.96(9)° in the title compound.
The title compound, \(C_{19}H_{17}PS_2\), results from the direct deprotonation of diphenylmethylphosphine sulfide and subsequent reaction with diphenyl disulfide. The C-P and C-S bond lengths of 1.8242 (18) and 1.8009 (18) Å, respectively, of the central P-C-S linkage are comparable to those found in the sulfonyl analogue, but are considerably longer than those reported for the dimetallated sulfonyl compound. The dihedral angle between the benzene rings of the diphenylmethyl moiety is 69.46 (7)°. No distinct intermolecular interactions are present in the crystal structure.
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.
Phosphines are important ligands in homogenous catalysis and have been crucial for many advances, such as in cross-coupling, hydrofunctionalization, or hydrogenation reactions. Herein we report the synthesis and application of a novel class of phosphines bearing ylide substituents. These phosphines are easily accessible via different synthetic routes from commercially available starting materials. Owing to the extra donation from the ylide group to the phosphorus center the ligands are unusually electron-rich and can thus function as strong electron donors. The donor capacity surpasses that of commonly used phosphines and carbenes and can easily be tuned by changing the substitution pattern at the ylidic carbon atom. The huge potential of ylide-functionalized phosphines in catalysis is demonstrated by their use in gold catalysis. Excellent performance at low catalyst loadings under mild reaction conditions is thus seen in different types of transformations.
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.