Modulation of Rotational Dynamics in Halogen-Bonded Cocrystalline Solids.

Dynamic processes are responsible for the functionality of a range of materials, biomolecules, and catalysts. We report a detailed systematic study of the modulation of methyl rotational dynamics via the direct and the indirect influence of noncovalent halogen bonds. For this purpose, a novel series of cocrystalline architectures featuring halogen bonds (XB) to tetramethylpyrazine (TMP) is designed and prepared using gas-phase, solution, and solid-state mechanochemical methods.

C-demethylation and 1, 2-amino shift in (E)-2-(1-(3-aminophenyl) ethylidene)hydrazinecarboxamide to (E)-2-(2-aminobenzylidene)hydrazinecarboxamide and their applications.

A Novel (E)-2-(1-(3-aminophenyl)ethylidene)hydrazinecarboxamide 1 was synthesized by traditional method and converted to (E)-2-(2-aminobenzylidene)hydrazinecarboxamide 2 by single step in DMSO at room temperature. Synthesized compound 1 was analysed by spectroscopy (NMR and LC-MS) techniques and molecule 2 was characterized using single crystal X-ray diffraction and spectroscopy (NMR and GC-MS) techniques. These analytical technique results revealed that, C-demethylation and 1, 2 amino shift in phenyl ring of compound 1 gives molecule 2.

Characterization of (Boc-Cys/Sec-NHMe) and (Boc-Cys/Sec-OMe) : Evidence of local conformational difference between disulfide and diselenide.

Conformations of disulfide and diselenide were compared in (Boc-Cys/Sec-NHMe) and (Boc-Cys/Sec-OMe) using X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, density functional theory (DFT), and circular dichroism (CD) spectroscopy. Conformations of disulfide/diselenide in polypeptides are defined based on the sign of side chain torsion angle χ (-CH -S/Se-S/Se-CH -); negative indicates left-handed and positive indicates right-handed orientation. In the crystals of (Boc-Cys-OMe) and (Boc-Sec-OMe) , the disulfide exhibits a left-handed and the diselenide a right-handed orientation.

Highly regio- and diastereoselective [3 + 2]-cycloadditions involving indolediones and α,β-disubstituted nitroethylenes.

A highly diastereoselective [3 + 2]-cycloaddition strategy involving multiple oxindoles and several α,β-disubstituted nitroethylenes is developed to access tetra-substituted α-spiropyrrolidine frameworks. A variety of α-amino acids were employed for the first time in order to generate azomethine ylides under thermal conditions, affording regioisomers 13 and 14 merely by changing the α-substituents (R = H and substituted carbons) of the α-amino acids. The reaction tolerates various sterically demanding, electron-rich and electron-deficient aryl and nitrogen substituents on glycines, oxindoles and nitroethylenes.