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 silylnitronate and the unactivated double bond. Finally, the fused isoxazoline can be further transformed to various cyclopentanoids.