Conversion of a C(sp(2))-H or C(sp(3))-H bond to the corresponding C-Me bond can be achieved by using AlMe3 or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.
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http://dx.doi.org/10.1021/jacs.5b04818 | DOI Listing |
Angew Chem Int Ed Engl
July 2018
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
The first rhodium(I)-catalyzed enantioselective intermolecular Csp3 -H activation of various saturated aza-heterocycles including tetrahydroquinolines, piperidines, piperazines, azetidines, pyrrolidines, and azepanes is presented. The combination of a rhodium(I) precatalyst and a chiral monodentate phosphonite ligand is shown to be a powerful catalytic system to access a variety of important enantio-enriched heterocycles from simple starting materials. Notably, the Csp3 -H activation of tetrahydroquinolines is especially challenging due to the adjacent Csp2 -H bond.
View Article and Find Full Text PDFOrg Lett
August 2016
School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458, China.
An efficient copper-catalyzed selective cross coupling of imidazo[1,2-a]pyridines with methyl hetarenes has been reported. This transformation opened a new route to synthesize the C-3 carbonyl imidazo[1,2-a]pyridine derivative, which is a common structural motif in natural products and pharmaceuticals. (18)O-labeling experiments indicated that the oxygen source of products originated from O2.
View Article and Find Full Text PDFChemistry
June 2016
Aix Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397, Marseille, France.
A straightforward synthesis of air- and water-stable bis-cationic macrocyclic imidazolylboronium anion receptors is described herein. By taking advantage of the bulky and rigid 9-borabicyclo[3.3.
View Article and Find Full Text PDFJ Org Chem
May 2015
Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States.
We report a modular approach to catalytic reductive Csp2-H and Csp3-H silylation of carboxylic acid derivatives encompassing esters, ketones, and aldehydes. Choice of either an Ir(I)/Rh(I) or Rh(I)/Rh(I) sequence leads to either exhaustive reductive ester or reductive ketone/aldehyde silylation, respectively. Notably, a catalyst-controlled direct formation of doubly reduced silyl ethers is presented, specifically via Ir-catalyzed exhaustive hydrosilylation.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2012
EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK.
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