Iron(III)-Catalyzed and Air-Mediated Tandem Reaction of Aldehydes, Alkynes and Amines: An Efficient Approach to Substituted Quinolines
作者:Ke Cao、Fu-Min Zhang、Yong-Qiang Tu、Xiao-Tao Zhuo、Chun-An Fan
DOI:10.1002/chem.200900875
日期:2009.6.22
Economic and practical advantages are offered by the iron(III)‐catalyzed and air‐mediated tandem coupling/hydroarylation/dehydrogenation of simple readily available aldehydes, alkynes, and amines for the synthesis of 2, 4‐disubstituted quinolines (see scheme).
Mechanistic Insights into the B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Initiated Aldehyde–Aniline–Alkyne Reaction To Form Substituted Quinolines
作者:Valerio Fasano、James E. Radcliffe、Michael J. Ingleson
DOI:10.1021/acs.organomet.7b00174
日期:2017.4.24
A substoichiometric quantity of the Lewis acid B(C6F5)(3) is sufficient to initiate the aldehyde-amine-alkyne reaction, in a one-pot methodology that enables the synthesis of a range of functionalized quinolines. Optimization studies revealed that key requirements for the high-yielding tricomponent reaction initiated by B(C6F5)(3) at raised temperatures include an excess of the in situ generated imine (which acts as a hydrogen acceptor) and an alkyne substituent able to stabilize positive charge buildup during the cyclization. Mechanistic experiments revealed that under these conditions B(C6F5)(3) is acting as a Lewis acid-assisted Bronsted acid; with H2O-B(C6F5)(3) being the key species enabling catalytic quinoline formation. This was indicated by deuterium labeling studies and the observation that the cyclization of N-(3-phenylpropargyl)aniline using B(C6F5)(3) under anhydrous conditions afforded the zwitterion [N-H-3-B(C6F5)(3)-4-Ph-quinolinium], which does not undergo protodeboronation to release B(C6F5)(3) and the quinoline product under a range of conditions. Finally, a brief substrate scope exploration demonstrated that this is an operationally Simple and effective methodology for the production of functionalized quinolines.
Enantioselective Metal-Free Hydrogenations of Disubstituted Quinolines
作者:Zhenhua Zhang、Haifeng Du
DOI:10.1021/acs.orglett.5b03307
日期:2015.12.18
A metal-freehydrogenation of 2,4-disubstituted quinolines was realized for the first time using chiral diene derived borane catalysts to furnish the corresponding tetrahydroquinolines in 75–98% yields with 95/5−99/1 dr’s and 86–98% ee’s. This catalytic system was also effective for 2,3-disubstituted quinolines to give moderate to good ee’s.