Asymmetric Synthesis of Hydrocarbazoles Catalyzed by an Octahedral Chiral-at-Rhodium Lewis Acid.
A bis-cyclometalated chiral-at-metal rhodium complex catalyzes the Diels-Alder reaction between N-Boc-protected 3-vinylindoles (Boc = tert-butyloxycarbonyl) and β-carboxylic ester-substituted α,β-unsaturated 2-acyl imidazoles with good-to-excellent regioselectivity (up to 99:1) and excellent diastereoselectivity (>50:1 d.r.) as well as enantioselectivity (92-99% ee) under optimized conditions. The rhodium catalyst serves as a chiral Lewis acid to activate the 2-acyl imidazole dienophile by two-point binding and overrules the preferred regioselectivity of the uncatalyzed reaction.
Key Laboratory for Chemical Biology of Fujian Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, People's Republic of China.
Yong
Y
Huang
Key Laboratory for Chemical Biology of Fujian Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, People's Republic of China.
Liangliang
L
Song
Key Laboratory for Chemical Biology of Fujian Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, People's Republic of China. gongl@xmu.edu.cn.
Lei
L
Gong
Key Laboratory for Chemical Biology of Fujian Province and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, People's Republic of China. meggers@xmu.edu.cn, meggers@chemie.uni-marburg.de.|Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany. meggers@xmu.edu.cn, meggers@chemie.uni-marburg.de.
Eric
E
Meggers
D002227:Carbazoles / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D007093:Imidazoles / Q000737:chemistry; D058116:Lewis Acids / Q000737:chemistry*; D008968:Molecular Conformation; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D002227:Carbazoles; D007093:Imidazoles; D058116:Lewis Acids; C029899:imidazole; D012238:Rhodium
Diels-Alder; asymmetric catalysis; chiral-at-metal; hydrocarbazoles; rhodium