ABSTRACT
A catalytic conjunctive cross-coupling reaction is developed that allows the construction of chiral organoboronic esters from alkylboron ate complexes and alkyl iodide electrophiles. The process occurs most efficiently with a Ni/Pybox-comprised catalyst and with an acenapthoquinone-derived boron ligand. Because of the broad functional group tolerance of this reaction, it can be a versatile tool for organic synthesis. Applications to the construction of (R)-coniine and (-)-indolizidine 209D are described.
Subject(s)
Alkaloids/chemical synthesis , Boronic Acids/chemical synthesis , Esters/chemical synthesis , Indolizines/chemical synthesis , Nickel/chemistry , Piperidines/chemical synthesis , Alkaloids/chemistry , Boronic Acids/chemistry , Catalysis , Esters/chemistry , Indolizines/chemistry , Molecular Structure , Piperidines/chemistryABSTRACT
ß-Boryl carbonyl compounds are produced by a Ni-catalyzed cross-coupling of vinylboron "ate" complexes and acid chloride or acid anhydride electrophiles. The reactions are efficient, being complete in as little as two minutes, and can be applied to a broad range of substrates.
Subject(s)
Boron/metabolism , Carboxylic Acids/metabolism , Catalysis , Humans , Organic ChemicalsABSTRACT
A method for enantioselective direct α-amination reaction catalyzed by a sterically "frustrated" Lewis acid/Brønsted base complex is disclosed. Cooperative functioning of the Lewis acid and Brønsted base components gives rise to in situ enolate generation from monocarbonyl compounds. Subsequent reaction with hydrogen-bond activated dialkyl azodicarboxylates delivers α-aminocarbonyl compounds in high enantiomeric purity.
ABSTRACT
Oligomeric thiophenes are commonly used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nanoaggregates of three sexithiophene oligomers having different alkyl substitution patterns were formed using solvent-poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changes and their dependence on substitution are well-modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain-packing configurations within the aggregates, with their measured electronic spectra.
