A new family of carbon‐bound boron enolates, generated by a kinetically controlled halogen exchange between chlorocatecholborane and silylketene acetals, is described. These C−boron enolates are demonstrated to activate 1,3‐enyne substrates in the presence of a Pd0/Senphos ligand complex, resulting in the first examples of a carboboration reaction of an alkyne with enolate‐equivalent nucleophiles. Highly substituted dienyl boron building blocks are produced in excellent site‐, regio‐, and diastereoselectivity by the described catalytic cis‐carboboration reaction.
A new Zn‐N4‐Schiff base L=((±)‐trans‐N,N’‐Bis(2‐aminobenzylidene)‐1,2‐diaminocyclohexane) complex was synthesized and fully characterized, showing an unexpected self‐assembled double‐stranded helicate structure. The X‐ray crystal analysis of the Zn2L2 complex ((C40H44N8Zn2,CH2Cl2, a=14.2375(3) Å, b=16.7976(4) Å, c=16.1613(4) Å, monoclinic, P21/n, Z=4) shows a centrosymmetrical structure in which zinc atoms are in distorted tetrahedral environments, revealing an M‐ (R, R) left‐handed helicity in its asymmetric unit. However, it was observed that this dinuclear complex is thermodynamically unstable in the presence of small water amounts and undergoes demetallation into free N4‐Schiff base ligand and ZnO nanoparticles. This hydrolysis process was thoroughly identified and monitored through detailed 1H NMR, DOSY NMR analysis. The reaction mechanism of this demetallation event was elucidated by using the DFT method, involving an activation energy smaller than 13 kcal/mol. Besides, a theoretical mechanism of the demetallation process is given for the first time.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.