Highly stereoselective oxy-Michael additions to alpha,beta-disubstituted nitro olefins: asymmetric synthesis of pseudo-norephedrine derivatives and THP* protected alpha-hydroxy ketones.
The "naked" anion of (S)-6-methyl delta lactol undergoes efficient oxy-Michael addition to alpha,beta-disubstituted nitro olefins to give the THP* protected Henry products with excellent (95-->98% de) stereocontrol at the beta-position and moderate (up to 3 : 1) stereocontrol at the alpha-position in favour of the syn-diastereoisomer. Nitro group reduction with in situN-Boc protection and THP* removal provides alpha,beta-disubstituted ethanolamine derivatives, while treatment with tetrapropylammonium perruthenate gives THP* protected alpha-hydroxy ketone derivatives in high diasteromeric excess.
Department of Chemistry, University of Cambridge, UK.
David J
DJ
Buchanan
Darren J
DJ
Dixon
Felix A
FA
Hernandez-Juan
D000475:Alkenes / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D010665:Phenylpropanolamine / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D007659:Ketones; C005331:norpseudoephedrine; D010665:Phenylpropanolamine