Catalytic Asymmetric Hydrogenation of N-Boc-Imidazoles and Oxazoles
摘要:
Substituted imidazoles and oxazoles were respectively hydrogenated into the corresponding chiral imidazolines and oxazolines (up to 99% ee). The highly enantioselective hydrogenation was achieved by using the chiral ruthenium catalyst, which is generated from Ru(eta(3)-methallyl)(2)(cod) and a trans-chelating chiral bisphosphine ligand, PhTRAP. This is the first successful catalytic asymmetric reduction of 5-membered aromatic rings containing two or more heteroatoms.
Catalytic Asymmetric Hydrogenation of N-Boc-Imidazoles and Oxazoles
摘要:
Substituted imidazoles and oxazoles were respectively hydrogenated into the corresponding chiral imidazolines and oxazolines (up to 99% ee). The highly enantioselective hydrogenation was achieved by using the chiral ruthenium catalyst, which is generated from Ru(eta(3)-methallyl)(2)(cod) and a trans-chelating chiral bisphosphine ligand, PhTRAP. This is the first successful catalytic asymmetric reduction of 5-membered aromatic rings containing two or more heteroatoms.
Synthesis of Substituted Oxazoles by Visible-Light Photocatalysis
作者:Tanmay Chatterjee、Ji Young Cho、Eun Jin Cho
DOI:10.1021/acs.joc.6b00989
日期:2016.8.19
A simple and practical method for the synthesis of substituted oxazoles has been developed using readily available α-bromoketones and benzylamines by visible-light photocatalysis at room temperature. The process, which requires 1 mol % of [Ru(bpy)3]Cl2 photocatalyst with K3PO4 and CCl3Br, is effective for accessing a variety of valuable oxazole compounds. The synthetic utility of our protocol was also
已经开发了一种简单而实用的合成取代的恶唑的方法,该方法使用易得的α-溴代酮和苄胺,在室温下通过可见光光催化进行合成。该方法需要1摩尔%的具有K 3 PO 4和CCl 3 Br的[Ru(bpy)3 ] Cl 2光催化剂,可有效地获得各种有价值的恶唑化合物。我们的协议的合成效用也通过制备天然产物texaline得到了证明。
C-H Bond Activation: A Versatile Protocol for the Direct Arylation and Alkenylation of Oxazoles
The versatile palladium complex Pd(PPh3)4 catalyses both direct arylation and alkenylation of oxazoles efficiently. The method is regioselective and stereospecific with respect to bromoalkenes and tolerates a wide range of functional groups.
Copper-catalyzed oxidative cyclization of chalcone and benzylic amine leading to 2,5-diaryl oxazoles via carbon–carbon double bond cleavage
作者:Dongfang Liu、Jintao Yu、Jiang Cheng
DOI:10.1016/j.tet.2013.12.077
日期:2014.2
oxidative cyclization of chalcone with benzylic amine is achieved, providing 2,5-diaryl oxazoles in moderate to good yields. The procedure employs O2 as a clean oxidant and involves an oxidative cleavage of the CC bond as the key step.
Rhodium-Catalyzed Oxidative 1:1, 1:2, and 1:4 Coupling Reactions of Phenylazoles with Internal Alkynes through the Regioselective Cleavages of Multiple C−H Bonds
selectively through the coupling of 1-phenylpyrazole and diphenylacetylene in 1:1, 1:2, and 1:4 manners, respectively. The reactions preferentially take place at the electron-deficient sites on the aromatic substrates. A comparison of reactivities of variously substituted and deuterated substrates sheds light on the mechanism of C−H bond cleavage steps. The reaction pathway is highly dependent on reaction