Asymmetric Michael addition of 2-nitropropane to a chalcone catalyzed by chiral crown ethers incorporating a D-glucose unit

✍ Scribed by Péter Bakó; László Töke; Áron Szöllösy; Petra Bombicz

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 173 KB
• Volume: 8
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/(sici)1098-1071(1997)8:4<333::aid-hc8>3.0.co;2-b

✦ Synopsis

Michael addition of 2-nitropropane 4 to a chalcone 3 catalyzed by crown ethers incorporating two glucose units (of 1 type) afforded the adduct 5 with an R-enantiomer excess (28% ee) while the aza-crown ethers containing one glucose unit (of 2 type) gave the same adduct favoring the S-enantiomer under solid-liquid phase transfer conditions (SL-PT). It was proven that substituents at the N-atom of the crown ring in 2 have a significant effect on both the chemical yield and the enantioselectivity, and those having heteroatoms in the proper position of the side chain (2e, 2f) showed the best results in this reaction: 65% ee for the S-antipode. The absolute configuration of (‫-4-)ם‬methyl-4nitro-1,3-diphenyl-1-pentanone (5), determined by Xray diffraction, is also presented in this article.