Borane‐Catalyzed Tandem Cyclization/Hydrosilylation Towards Enantio‐ and Diastereoselective Construction of trans‐2,3‐Disubstituted‐1,2,3,4‐Tetrahydroquinoxalines
Borane‐Catalyzed Tandem Cyclization/Hydrosilylation Towards Enantio‐ and Diastereoselective Construction of trans‐2,3‐Disubstituted‐1,2,3,4‐Tetrahydroquinoxalines
Indium metal as a reducing agent in organic synthesis
作者:Michael R. Pitts、Justin R. Harrison、Christopher J. Moody
DOI:10.1039/b101712h
日期:——
aromatic nitrocompounds under similar conditions results in selectivereduction of the nitro groups; ester, nitrile, amide and halide substituents are unaffected. Likewise indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters. Indium is also an effective reducing agent under non-aqueous conditions and α-oximino carbonyl compounds can
A Highly<i>cis</i>-Selective and Enantioselective Metal-Free Hydrogenation of 2,3-Disubstituted Quinoxalines
作者:Zhenhua Zhang、Haifeng Du
DOI:10.1002/anie.201409471
日期:2014.11.13
A wide range of 2,3‐disubstituted quinoxalines have been successfully hydrogenated with H2 using borane catalysts to produce the desired tetrahydroquinoxalines in 80–99 % yields with excellent cis selectivity. Significantly, the asymmetric reaction employing chiral borane catalysts generated by the in situ hydroboration of chiral dienes with HB(C6F5)2 under mild reaction conditions has also been achieved
使用硼烷催化剂已成功地将多种2,3-二取代的喹喔啉用H 2氢化,以80-99%的产率产生所需的四氢喹喔啉,并具有出色的顺式 选择性。值得注意的是,在温和的反应条件下,采用手性二硼烷与HB(C 6 F 5)2进行手性二烯氢硼化生成的手性硼烷催化剂的不对称反应也达到了96%ee,这是第一个催化不对称体系。提供光学活性的顺式-2,3-二取代的1,2,3,4-四氢喹喔啉。
A rapid and efficient method for the reduction of quinoxalines
作者:Andrew M. McKinney、Kevin R. Jackson、Ralph Nicholas Salvatore、Elena-Maria Savrides、Mary Jane Edattel、Terrence Gavin
DOI:10.1002/jhet.5570420546
日期:2005.7
Mono and di-substituted alkyl and aryl quinoxalines are rapidly reduced in high yield to their respective 1,2,3,4-tetrahydro-derivatives by borane in THF solution. In the case of the 2,3-di-substituted compounds, reduction is stereoselective yielding exclusively the cis-isomers. Sodium borohydride in acetic acid also reduces alkyl and aryl quinoxalines, but proceeds with lower yields and often produces
Transfer hydrogenation of unsaturated nitrogen heterocycles using a rhodiumcatalyst immobilized on bipyridine-periodic mesoporous organosilica (BPy-PMO) is described. The immobilized catalyst was prepared by mixing [Cp*RhCl2]2 (Cp* = η5-C5Me5) with BPy-PMO powder in DMF at 60 °C and characterized by nitrogen adsorption measurements, solid-state NMR spectroscopy, X-ray diffraction, energy-dispersive
Asymmetric Transfer Hydrogenations of 2,3-Disubstituted Quinoxalines with Ammonia Borane
作者:Songlei Li、Wei Meng、Haifeng Du
DOI:10.1021/acs.orglett.7b00935
日期:2017.5.19
An asymmetrictransferhydrogenation of 2,3-disubstituted quinoxalines using a chiral frustrated Lewis pair of Piers’ borane and (R)-tert-butylsulfinamide as the catalyst with ammoniaborane as the hydrogen source has been successfully realized. For 2-alkyl-3-arylquinoxaline substrates, cis-tetrahydroquinoxalines were obtained as the predominant products in high yields with 77–86% ee. In contrast,