Cinchona alkaloid-lewis acid catalyst systems for enantioselective ketene-aldehyde cycloadditions.
Asymmetric cinchona alkaloid-catalyzed acid chloride-aldehyde cyclocondensation (AAC) reactions afford enantioenriched 4-substituted and 3,4-disubstituted beta-lactones with near perfect absolute and relative stereocontrol. These reactions are characterized by the operational simplicity derived from using commercially available or easily obtained (one-step) reaction catalysts and in situ ketene generation from acid chlorides. The range of aldehyde substrates that serve as effective AAC substrates include sterically hindered aldehydes such as cyclohexanecarboxaldehyde and pivaldehyde.
Zhu
Cheng
C
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Shen
Xiaoqiang
X
Nelson
Scott G
SG
D000143:Acids / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D002930:Cinchona Alkaloids / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism
D000143:Acids; D000447:Aldehydes; D002930:Cinchona Alkaloids; D005030:Ethylenes; D007659:Ketones; C008223:ketene