STUDIES ON DIASTEREOSELECTIVE ADDITIONS OF 2-SUBSTITUTED CYCLOPENTANONES TO BETA-NITROSTYRENE

The Michael addition of 2-substituted cyclopentanones 1 to beta-nitros tyrene 2 proceeds at room temperature in the presence of catalysts suc h as NEt(3), DMAP, KOAc, or Ni(acac)(2) leading to 2-substituted 2-(2- nitro-1-phenylethyl)cyclopentanones 3/4. Depending on substituents R i n 1 compounds rac-3/4 may be obtained with high diastereoselectivity. The influences of reaction conditions were studied and the diastereome ric ratio was determined by means of H-1-NMR spectroscopy. In the case s of rac-3/4a-c, rac-3g-i, rac-3k, the diastereomers could be isolated in pure form. The configuration of compounds rac-3a and rac-4a was es tablished from X-ray crystallography.