184592-91-4Relevant articles and documents
Orientation-dependent conformational polymorphs in two similar pyridine/pyrazine phenolic esters
Samie, Ali,Salimi, Alireza
, p. 3721 - 3730 (2019/06/21)
On the basis of crystal engineering, two similar esters of phenyl pyridine-2-carboxylate (I) and phenyl pyrazine-2-carboxylate (II) were designed and synthesized. The compounds were characterized using FT-IR, mass spectrometry, CHN-elemental analyses, NMR and PXRD. For each compound, two polymorphs were obtained (Ia, Ib and IIa, IIb) and identified by TGA, DSC and SCXRD. A comparison of the crystal structures of the polymorphs revealed that the different torsion angles of the pyrazine (τ1) and phenyl (τ2) rings to the ester backbone resulted in the conformers I and II, respectively. Theoretical criteria (max(Δθ), rmsd[r]-crystal, energy profile) confirmed that the structural differences in the conformers are in the range of acceptable values for the detection of conformational changes. The phase stability of the polymorphs was investigated by slurry and grinding methods as well as by the HSM technique. Since the orientations of pyrazine and phenyl moieties were altered in the polymorphs, the hydrogen bond donor and acceptors exhibited meaningful supramolecular architectures in the crystal packing as well as C-H?N, C-H?O and C-H?π interactions. The energetic study of the noncovalent interactions in the molecular pairs (dimers) of the polymorph crystal structures was performed by DFT-D calculations.
Nickel-Catalyzed Decarbonylative Coupling of Aryl Esters and Arylboronic Acids
Laberge, Nicole A.,Love, Jennifer A.
supporting information, p. 5546 - 5553 (2015/09/01)
A variety of functionalized biaryls can be accessed by coupling aryl and heteroaryl esters with boronic acids in Suzuki-Miyaura-type decarbonylative cross-coupling catalyzed by an affordable catalyst system composed of Ni(cod)2 and PCy3. The methodology is tolerant of a variety of functional groups and presents an attractive alternative to the use of palladium catalysis currently used in industry to acquire such bis(hetero)aryls, but also reveals challenges associated with nickel catalysis of esters in cross-coupling chemistry.
