Pd-Catalyzed Regio- and Atroposelective Hydroalkynylation of Allene to Access Axially Chiral Conjugated 1,3-Enynes

The efficient synthesis of regio- and stereodefined multisubstituted conjugated 1,3-enynes, particularly those with axial chirality, remains challenging and underdeveloped. In this work, an efficient atroposelective hydroalkynylation of allene is established precisely synthesizing a broad range of conjugated 1,3-enynes containing a chiral C–N axis or C–C axis with high functional group tolerance (>80 examples), excellent atroposelectivity, regioselectivity, and E-selectivity. Notably, this strategy could provide atropisomers with up to three stereogenic axes with excellent enantioselectivity (up to 99% ee). The further transformation of the carbon–carbon triple bond enables efficient construction of various acyclic C–C or C–N axially chiral tetrasubstituted alkenes.