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.
Photochemical Transformation of <i>O</i>
-(β-Arylethyl) Arylimidates into 2,4-Diaryl-5-iodoxazoles with 1,3-Diiodo-5,5-dimethylhydantoin
作者:Aya Saito、Hideo Togo
DOI:10.1002/ejoc.202000383
日期:2020.6.16
2,4‐Diaryl‐5‐iodoxazoles could be obtained by the treatment of O ‐(β‐arylethyl) arylimidates with 1,3‐diiodo‐5,5‐dimethylhydantoin (DIH) under irradiation with a tungsten lamp. This reaction proceeds through multiple stets, i.e., formation of N ‐iodoimidate, iminyl radical, 1,5‐H shift, 5‐exo‐tet cyclization to oxazoline, oxidation to oxazole, and iodination to 5‐iodoxazole.
A new and efficient method for the synthesis of 4-aryl-2-phenyloxazoles is described which is based upon the reaction of α-[(2,4-dinitrobenzene)sulfonyl]oxy ketone intermediates with benzamide in ionicliquid.
Radical cascade synthesis of azoles <i>via</i> tandem hydrogen atom transfer
作者:Andrew D. Chen、James H. Herbort、Ethan A. Wappes、Kohki M. Nakafuku、Darsheed N. Mustafa、David A. Nagib
DOI:10.1039/c9sc06239d
日期:——
A radical cascade enables rapid, modular access to five-membered heteroarenes, including oxazoles and imidazoles, through a regio- and chemo-selective β C–H bis-functionalization.
Catalytic Asymmetric Hydrogenation of N-Boc-Imidazoles and Oxazoles
作者:Ryoichi Kuwano、Nao Kameyama、Ryuhei Ikeda
DOI:10.1021/ja201543h
日期:2011.5.18
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.
Divergent Palladium‐Catalyzed Tandem Reaction of Cyanomethyl Benzoates with Arylboronic Acids: Synthesis of Oxazoles and Isocoumarins
A palladium‐catalyzed tandem reaction of cyanomethyl benzoates with arylboronic acids has been achieved. Substitution at the 2‐position of cyanomethyl benzoates was found to be crucial for the selective synthesis of oxazoles and isocoumarins. Cyanomethyl benzoates afforded 2,4‐diaryloxazoles as products, while 2‐benzoyl‐substituted cyanomethyl benzoates delivered 3‐benzoyl‐4‐aryl‐isocoumarins selectively