Trimetallic PEPPSI‐Type Palladium N‐Heterocyclic Carbene Complexes – Improved Catalyst Lifetime in the Mizoroki–Heck Coupling Reaction
作者:Francisco Martínez‐Olid、Román Andrés、Juan C. Flores、Pilar Gómez‐Sal
DOI:10.1002/ejic.201500542
日期:2015.8
(pyridine-enhanced precatalyst preparation stabilization and initiation) complexes bearing N-heterocycliccarbene (NHC) ligands containing a protected amine in the form of an ethylphthalimido group have been synthesized. These discrete prototypes of complexes covalently bound to suitable supports have been studied in the Mizoroki–Heck coupling of aryl iodides under mild conditions, including sets of experiments
The tripodal linker unit with one bromopropyl group and three anchoring silicon atoms was used to immobilize a chiral phosphine–rhodium complex catalyst on an ordered mesoporous silica support. The rhodium and phosphorus leaching levels into the reaction solution after asymmetric hydrogenation were lower for this catalyst than for immobilized catalysts prepared using conventional triethoxysilane.
Cyclisation reactions of dienyl- and enynylsilanes by carbon–carbon bond formation under RCM conditions yield five-, six- and seven-membered silacycloalkenes. The relative ease of ringformation from dienes was in the order six->seven->five-memberedrings. A conjugated vinylsilacyclopentene was formed from the corresponding enyne substrate. Silaspirenes have been prepared from silacarbacycles by the
Divergent synthesis of carbosilane wedges as dendritic building blocks: a new strategy towards core functionalised carbosilane dendrimers
作者:Rieko van Heerbeek、Joost N.H. Reek、Paul C.J. Kamer、Piet W.N.M. van Leeuwen
DOI:10.1016/s0040-4039(99)01476-8
日期:1999.9
A divergent route for the synthesis of carbosilane wedges containing either a bromine or amine as a focal point has been developed for the construction of core functionalised dendrimers; carbosilanedendrimersup to the third generation containing a 1,3,5-benzene triamide core capable of binding guest molecules via hydrogen bonding have been prepared.
The design and synthesis of a new linkerunit that will enable uniform and robust immobilization of organic functional molecules onto silica supports is described. This linkerunit works as a rigid...