A general organocatalytic enantioselective malonate addition to alpha,beta-unsaturated enones.
A general enantioselective organocatalytic conjugate addition procedure of a variety of malonates to alpha,beta-unsaturated enone systems is presented. The reaction is efficiently catalysed by the pyrrolidinyl tetrazole catalyst 1. Cyclic, acyclic and aromatic enones can be used and the reaction with ethyl malonates 3 b provides the Michael addition products in high yields with good to excellent enantioselectivities. Since only 1.5 equivalents of malonate are used as a reagent, the reaction is readily scaled and practical to operate. Furthermore, the malonate addition products can be easily mono decarboxylated without loss in enantiomeric excess by enzymatic or sodium hydroxide mediated methods.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Veit
V
Wascholowski
Kristian Rahbek
KR
Knudsen
Claire E T
CE
Mitchell
Steven V
SV
Ley
D002384:Catalysis; D004951:Esterification; D005030:Ethylenes / Q000737:chemistry; D008314:Malonates / Q000737:chemistry*; D015394:Molecular Structure; D012997:Solvents; D013237:Stereoisomerism
D005030:Ethylenes; D008314:Malonates; D012997:Solvents; C036216:ethylene; C030290:malonic acid