Effects of Geometric Isomers in Cyclopropane‐Based Bisoxazoline Ligands on the Asymmetric Diels‐Alder reaction and Cyclopropanation

Abstract Four new bisoxazoline ligands 2a – 2d containing trans cyclopropane unit have been synthesized through cyclization of the new dihydroxy diamides 5a – 5d . The catalytic activity, diastereoselectivity and asymmetric induction between the cis ligands 1a – 1d and the trans ligands 2a – 2d in copper‐catalyzed Diels–Alder reaction and cyclopropanation have been compared. Geometric isomers in cyclopropane‐based bisoxazoline ligands did not exhibit significantly different catalytic activity and diastereoselectivity. However, all the cis ligands except 1c showed higher enantioselectivity than the trans isomers.