Enantioselective aza-Diels-Alder reaction of aldimines with "Danishefsky-type diene" catalyzed by chiral scandium(III)-N,N'-dioxide complexes.
A new kind of complex prepared from scandium(III) triflate and l-proline-derived N,N'-dioxides has been developed to catalyze the enantioselective aza-Diels-Alder reaction between 1,3-butadiene (diene 1) and aldimines 2, affording the corresponding 2,5-disubstituted dihydropyridinones in moderate to high yields (up to 92%) with good enantioselectivities (up to 90% ee) at room temperature. A variety of aldimines including aromatic, heteroaromatic, conjugated, and aliphatic imines were found to be suitable substrates. Enantiopure samples (up to 99% ee) were obtained for some products by a single recrystallization. The absolute configuration of the products was determined by X-ray diffraction and CD analysis. On the basis of the investigation of 1H NMR spectra and the positive nonlinear effect, the catalyst structure was carefully discussed.
Shang
Deju
D
Key Laboratory of Green Chemistry & Technology, Sichuan University, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
Xin
Junguo
J
Liu
Yanling
Y
Zhou
Xin
X
Liu
Xiaohua
X
Feng
Xiaoming
X
D001372:Aza Compounds / Q000737:chemistry; D002070:Butadienes / Q000737:chemistry*; D002384:Catalysis; D003497:Cyclic N-Oxides / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011728:Pyridones / Q000138:chemical synthesis* / Q000737:chemistry; D012538:Scandium / Q000737:chemistry*; D013237:Stereoisomerism
D001372:Aza Compounds; D002070:Butadienes; D003497:Cyclic N-Oxides; D007097:Imines; D008024:Ligands; D009942:Organometallic Compounds; D011728:Pyridones; C031763:1,3-butadiene; D012538:Scandium