5625-44-5Relevant articles and documents
The Preparation and Resolution of Novel Axially Chiral Pyrazine-Containing P,N Ligands for Asymmetric Catalysis and Their Application in Palladium-Catalysed Allylic Substitution
Goddard, Richard,Guiry, Patrick J.,Kelly, Sarah
, (2022/01/04)
The design and synthesis of two novel pyrazine-containing ligands, 3,6-diisopropyl-Pyrazinap and Np?Cy-Pyrazinap, has been described. Their synthesis was accomplished in six and nine steps, respectively, in which the key steps were the formation of the biaryl linkage through a Suzuki cross-coupling reaction and the formation of the aryl to phosphorus bond employing nickel catalysis. Both ligands were resolved through the formation of diastereomeric palladacycles and in the case of the isolated diastereomer formed from 3,6-diisopropyl-Pyrazinap, an X-ray crystal structure showed the axial chirality to possess (S)-configuration. The two enantiopure ligands were applied to the palladium-catalysed allylic alkylation of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate and afforded conversions of up to 100 % and 99 % with enantioselectivities of up to 92 % ee and 78 % ee, respectively. A series of 1,1,3-triphenylallyl and 1,3-diphenylallyl palladium complexes were prepared and their solution structures and dynamic behaviour elucidated by 2D-COSY and NOESY NMR spectroscopic experiments.
Investigation of reaction mechanism of amino acids and phosphorus trichloride by 31P NMR and ESI-MS/MS
Cao, Yanchun,Cao, Shuxia,Xie, Yali,Zong, Xiangkun,Zhao, Yufen
experimental part, p. 1173 - 1179 (2012/04/23)
The reaction of amino acids and phosphorus trichloride in THF was studied by 31P NMR tracing and ESI-MS/MS. A series of hydridophoranes and cyclic dipeptides were obtained. The reaction presented interesting diversity and the reaction mechanism was proposed. The mechanism suggests that phosphorus plays an important role in the synthesis of amino acid hydridophorane and cyclic dipeptides. The results also show that 31P NMR and ESI-MS/MS are useful tools for the investigation of reaction mechanism. Copyright
A novel approach to the synthesis of symmetric optically active 2,5-dioxopiperazines
Basiuk,Gromovoy,Chuiko,Soloshonok,Kukhar
, p. 449 - 451 (2007/10/02)
'Gas-solid-phase' method for the preparation of some cyclic dipeptides,2,5-dioxopiperazines (diketopiperazines), is described. The method implies cyclodimerization of vaporous aliphatic α-amino acids in the presence of silica at reduced pressure and yields optically active 2,5-dioxopiperazines.
