Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis

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Title: Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis
Author: Reich, Blair Jesse Ellyn
Abstract: Cyanide -catalyzed aldimine coupling was employed to synthesize compounds with 1 ,2 -ene -diamine and ? ? ? ? -imine -amine structural motifs : 1 ,2 ,N ,N' - tetraphenyletheylene -1 ,2 -diamine (13 ) and (+ / - ) -2 ,3 -di - (2 -hydroxyphenyl ) -1 ,2 - dihydroquinoxaline (17 ) , respectively . Single crystal X -ray diffraction provided solidstate structures and density functional theory calculations were used to probe isomeric preferences within this and the related hydroxy -ketone /ene -diol system . The enediamine and imine -amine core structures were calculated to be essentially identical in energy . However , additional effects -such as ? ? ? ? conjugation -in 13 render an enediamine structure that is slightly more stable than the imine -amine tautomer (14 ) . In contrast , the intramolecular hydrogen bonding present in 17 significantly favors the imine -amine isomer over the ene -diamine tautomer (18 ) . Aldimine coupling (AIC ) is the nitrogen analogue of the benzoin condensation and has been applied to dialdimines , providing the first examples of cyclizations effected by cyanide -catalyzed AIC . Sodium cyanide promoted the facile , intramolecular cyclization of several dialdimines in N ,N -dimethylformamide , methanol , or dichloromethane /water (phase -transfer conditions ) yielding a variety of six -membered heterocycles . Under aerobic conditions , an oxidative cyclization occurs to provide the diimine heterocycle . Cyanide -catalyzed aldimine coupling was employed as a new synthetic method for oligomerization . Nine rigidly spaced dialdimines were oxidatively coupled under aerobic conditions to yield conjugated oligoketimines and polyketimines with unprecedented structure and molecular weight (DP = 2 - 23 , ~700 -8200 g /mol ) . The ? ? ? ? - diimine linkage was established based on IR spectroscopy , NMR spectroscopy , size exclusion chromatography , and X -ray crystallographic characterization of the model oxidized dimer of N -benzylidene - (p -phenoxy ) -aniline . Cyclic voltammetry indicates ptype electrical conductivity , suggesting they are promising candidates for plastic electronic devices . The cyanide -catalyzed benzoin condensation reaction of 4 -substituted benzaldehydes followed by oxidation to the diketone , and the Schiff Base condensation of two equivalents of o -aminophenol provides 2 ,3 - (4 -X -phenyl )2 -1 ,4 - (2 - hydroxyphenyl )2 -1 ,4 -diazabutadiene . The ligand is given the moniker X -dabphol . These ligands are readily metallated to form M -X -dabphol complexes . The copper complexes catalytically fix CO2 with propylene oxide to yield propylene carbonate . DFT studies along with a comparison with Hammet parameters help validate and elaborate on the catalytic cycle and the catalytic results obtained . The nickel complex is competent for olefin epoxidation . Synthesis , characterization , X -ray structure , DFT analysis , and catalytic activity of the parent nickel dabphol complex are reported .
URI: http : / /hdl .handle .net /1969 .1 /4987
Date: 2007-04-25

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Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis. Available electronically from http : / /hdl .handle .net /1969 .1 /4987 .

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