The strained olefins in trans-cyclooctenes serve as efficient catalysts for halolactonizations, including bromolactonizations and iodolactonizations. The trans-cyclooctene framework is essential for excellent catalytic performance, and the substituents also play important roles in determining efficiency. These results are the first demonstration of catalysis by a trans-cyclooctene.

trans‐Cyclooctenes serve as asymmetric ligands for the rhodium‐catalyzed 1,4‐additions of organotin reagents to enones. We demonstrate, for the first time, that these chiral olefins can provide efficient coordination spheres for asymmetric metal catalysis. As the asymmetric environment around the reaction site is constructed by the trans‐cyclooctene framework, the introduction of a substituent at the allylic position further improves enantioselectivity to 93 % ee. These findings provide new chiral framework designs for the asymmetric ligands of metal catalysts.

The strained olefins in trans-cyclooctenes serve as efficient catalysts for halolactonizations,i ncluding bromolactonizations and iodolactonizations.T he trans-cyclooctene framework is essential for excellent catalytic performance, and the substituents also play important roles in determining efficiency.These results are the first demonstration of catalysis by atrans-cyclooctene.