From Conjugated to Enantioenriched Skipped Dienes: Co-Catalyzed Asymmetric Cross-Hydrodimerization of 1,3-Dienes and Alkynes

Transition-metal-catalyzed asymmetric carbon-carbon bond-formation processes represent contemporary techniques for the straightforward and efficient construction of stereogenic carbon centers. However, transition-metal-catalyzed asymmetric carbon-carbon coupling in the absence of any directing group is highly desirable, yet remains extremely challenging. Herein, an unprecedented Co-catalyzed asymmetric cross-hydrodimerization of 1,3-dienes with alkynes has been developed to deliver enantioenriched skipped dienes under mild conditions, representing the first example of a Co-catalyzed asymmetric cross-hydrodimerization of unsaturated hydrocarbons. The reaction features the synthesis of chiral skipped dienes from conjugated dienes without using any prefunctionalized starting materials. Notably, chiral skipped dienes with minimally different substituents at 1,4-positions are easily synthesized, which are difficult to access otherwise. Furthermore, a wide range of 1,3-dienes with diverse substitution patterns as well as aliphatic and aryl, terminal, and internal alkynes with different electronic properties and steric hindrance are tolerated. In addition, this Co-catalyzed asymmetric cross-hydrodimerization is efficiently applied to the synthesis of the key intermediate of natural product Phorbasin C.