Studies on diastereoselective additions of 2-substituted cyclopentanones to ?-nitrostyrene
作者:J. Deutsch、H.-J. Niclas、M. Ramm
DOI:10.1002/prac.19953370105
日期:——
The Michael addition of 2-substituted cyclopentanones 1 to beta-nitrostyrene 2 proceeds at room temperature in the presence of catalysts such 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 in 1 compounds rac-3/4 may be obtained with high diastereoselectivity. The influences of reaction conditions were studied and the diastereomeric ratio was determined by means of H-1-NMR spectroscopy. In the cases 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 established from X-ray crystallography.
Organocatalytic asymmetric Michael addition of α-aryl cyclopentanones to nitroolefins for construction of adjacent quaternary and tertiary stereocenters
作者:Xiu-Qin Dong、Huai-Long Teng、Min-Chao Tong、He Huang、Hai-Yan Tao、Chun-Jiang Wang
DOI:10.1039/c0cc01987a
日期:——
The first asymmetric Michael addition of alpha-aryl cyclopentanones to nitroolefins for construction of adjacentquaternary and tertiarystereocenters has been achieved with excellent diastereo-/enantioselectivity.