STEREOSELECTIVE SYNTHESIS OF 3-(ETHOXYCARBONYL)-4-HYDROXY-5-(1-HYDROXYALKYL)-2-ISOXAZOLINE 2-OXIDES BY REACTION OF 2,3-EPOXY ALDEHYDES AND ETHYL NITROACETATE ON ALUMINA SURFACE

: Treatment of racemic 2,3-epoxy aldehydes and ethyl nitroacetate with alumina affords title compounds through a nitroaldol reaction—cyclization process. While in the case of 3-trans-monosubstituted substrates, C4,C5-trans and cis isomers (dr = 1.5) with C5,C6-anti configuration are obtained, 3-cis-monosubstituted 2,3-epoxy aldehydes give C4,C5-trans and cis derivatives with a much higher diastereoselectivity (dr > 20) and C5,C6-syn configuration. 5-Exo cyclization occurs also when 2,3-epoxy aldehydes are 2-substituted. © 1990, American Chemical Society. All rights reserved.