RESUMEN
We report a general approach to highly functionalized (Z)-allylic amines by decarboxylative allylation of vinyloxazolidin-2-ones. This process engages sodium sulfinates as nucleophiles to form a new carbon-sulfur bond, utilizing a palladium catalyst generated from Pd(OAc)2 and diphosphine ligand dpppe. The scope of the protocol is illustrated by the synthesis of 30 representative allylic amines with high regio- and stereoselectivity. Mechanistic studies show that the Z-selectivity of the reaction stems from the formation of a palladacycle intermediate through Pd-N chelation. The synthetic utility of this method was further exemplified by the gram-scale synthesis and subsequent transformations to various compounds.
RESUMEN
The effects of Ca(OH)2 on the physicochemical, mechanical and microstructural characteristics, intermolecular forces and protein patterns of preserved egg white (PEW) were investigated. Results suggested that Ca(OH)2 (0.1%) reduced the free alkalinity content and turbidity and increased the brightness of PEW. The surface hydrophobicity of PEW protein with added Ca(OH)2 decreased during the pickling period owing to the hydrophobic residues being hidden in the interior of the protein. Total content of sulfhydryl and disulfide bonds in PEW decreased. Non-specific cross-linking, hydrogen bonds and hydrophobic interactions were the primary intermolecular forces. For textural properties, hardness and springiness had obvious prominence. A loose porous and regular network-like microstructure formed as the Ca(OH)2 increased and Ca(OH)2 delayed denaturation of the PEW protein. The physical properties of PEW correlated with molecular interactions and the microenvironment. Ca(OH)2 improved the contribution of surface hydrophobicity, disulfide bonds and hydrophobic interactions to the gelation process.
