Sequential Organocatalyzed Michael Addition/[3 + 2]-Heterocyclization for the Stereoselective Synthesis of Fused-Isoxazoline Precursors of Enantiopure Cyclopentanoids
摘要:
We propose an asymmetric synthesis of functionalized cyclopentanoids bearing up to four stereogenic centers from easily accessible nitroalkenes and unsaturated aldehydes. The overall sequence includes an enantioselective organocatalytic Michael addition and a [3 + 2]-heterocyclization between an in situ generated silyInitronate and the unactivated double bond. Finally, the fused isoxazoline can be further transformed to various cyclopentanoids.
Sequential Organocatalyzed Michael Addition/[3 + 2]-Heterocyclization for the Stereoselective Synthesis of Fused-Isoxazoline Precursors of Enantiopure Cyclopentanoids
We propose an asymmetric synthesis of functionalized cyclopentanoids bearing up to four stereogenic centers from easily accessible nitroalkenes and unsaturated aldehydes. The overall sequence includes an enantioselective organocatalytic Michael addition and a [3 + 2]-heterocyclization between an in situ generated silyInitronate and the unactivated double bond. Finally, the fused isoxazoline can be further transformed to various cyclopentanoids.
Asymmetric Michael Reaction Catalyzed by Proline Lithium Salt: Efficient Synthesis of<scp>L</scp>-Proline and Isoindoloisoquinolinone Derivatives
作者:Kun Xu、Sheng Zhang、Yanbin Hu、Zhenggen Zha、Zhiyong Wang
DOI:10.1002/chem.201202409
日期:2013.3.11
Lithium makes it possible: The enantioselective Michael addition of aldehydes to nitroalkenes was catalyzed by the readily available proline lithium salt. Remarkably, the asymmetric Michael reaction was scaled up to 50 mmol with 23:1 d.r. and 90 % ee.