Triazole‐phosphine‐copper complexes (TAP−Cu) have been synthesized and applied as tunable and efficient catalysts for the selective synthesis of fluoro‐substituted 2‐aryl‐1H‐benzodimidazole and ...1‐benzyl‐2‐aryl‐1H‐benzodimidazole derivatives from simple alcohols in only one step. TAP−Cu exhibited excellent and tunable catalytic activity for both dehydrogenation and borrowing hydrogen reactions with more than 80 examples being demonstrated for the first time. It was observed that the ligand played a critical role in catalyst activity. Mechanistic studies and deuterium labeling experiments indicated that the reactions proceeded by an initial and reversible alcohol dehydrogenation resulting in a copper hydride intermediate. This was also supported by the direct observation of a diagnostic copper hydride signal by solid‐state infrared spectroscopy. The TAP−Cu‐H complex showed absorptions at 912 cm−1 that could be assigned to copper−hydride stretches. Furthermore, the direct trapping of an intermediate bisimine was also successfully performed.
A three‐component palladium‐catalyzed aminocarbonylation of aryl and heteroaryl sp2 C−H bonds using nitroarenes as the nitrogen source was achieved using Mo(CO)6 as the reductant and origin of the ...CO. This intermolecular C−H bond functionalization does not requires any exogenous ligand to be added, and our mechanism experiments indicate that the palladacycle catalyst serves two roles in the aminocarbonylation reaction: reduce the nitroarene to a nitrosoarene and activate the sp2 C−H bond.
C−H functionalization: A three‐component palladium‐catalyzed aminocarbonylation of sp2 C−H bonds using nitroarenes as the nitrogen source was achieved using Mo(CO)6 as the reductant and origin of the CO. This intermolecular C−H bond functionalization does not require any exogenous ligand to be added.
An examination of the asymmetric hydrogenation of arenes and heteroarenes is presented. A look at the use of asymmetric hydrogenation of quinolines is also presented.
NHC-Catalyzed Hydroacylation of Styrenes Schedler, Michael; Wang, Duo-Sheng; Glorius, Frank
Angewandte Chemie (International ed.),
February 25, 2013, Letnik:
52, Številka:
9
Journal Article
Recenzirano
New hydroacylation catalysts: Highly electron‐rich N‐heterocyclic carbenes (NHCs) facilitate the intermolecular hydroacylation of unstrained olefins. This unprecedented organocatalytic coupling joins ...simple and abundant aldehydes and styrenes to yield valuable ketone products. EWG=electron‐withdrawing group, EDG=electron‐donating group.
The development of a method that employs a two‐chamber reaction vessel and uses molybdenum hexacarbonyl Mo(CO)6 as the carbon monoxide (CO) source for the palladium‐catalyzed transformation of ...nitroarenes into indoles or imidazoles is reported. The scope and limitations of our method are illustrated with 23 examples. Experiments that indicate the mechanism of the CH bond amination reaction to be stepwise are also reported.
A convergent asymmetric disproportionation of dihydroquinoxalines for the synthesis of chiral tetrahydroquinoxalines using a metal/Brønsted acid relay catalysis system has been developed. The use of ...hydrogen gas as the reductant makes the convergent disproportionation an ideal atom-economical process. A dramatic reversal of enantioselectivity was observed in the reduction of quinoxalines because of the different steric demands in the 1,2- and 1,4-hydride transfer pathways.
In tandem: A divergent and enantioselective approach to 2,3‐disubstituted indolines was developed through consecutive Brønsted acid/Pd‐complex‐promoted tandem reactions from simple 2‐substituted ...indoles and aldehydes in one operation to give up to 98 % ee (see scheme; R1=H, F, or Me; R2=alkyl; R3=aryl or alkyl). Three Brønsted acid promoted steps and two Pd‐catalyzed hydrogenation steps were involved in this process.
A highly enantioselective Pd-catalyzed partial hydrogenation of simple 2,5-disubstituted pyrroles with a Brønsted acid as an activator has been successfully developed, providing chiral ...2,5-disubstituted 1-pyrrolines with up to 92% ee.
The highly enantioselective hydrogenation of 3‐aryl‐2H‐1,4‐benzoxazines was achieved using the (cyclooctadiene)iridium chloride dimer/(S)‐SegPhos/iodine {Ir(COD)Cl2/(S)‐SegPhos/I2} system as catalyst ...with up to 92% ee. The 3‐styryl‐2H‐1,4‐benzoxazine derivatives were also hydrogenated by the iridium catalyst and Pd/C in two consecutive steps whereby 93–95% ee values were obtained.
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