Visible Light-Induced Regioselective to Isomerization of Polarized 1,3-Dienes: Experimental and Theoretical Insights.

The stereocontrol of → isomerization on a (1,3)-diene, instead of a simple alkene, can be more challenging due to the increased number of isomerization possibilities. Herein, we report visible light-mediated regioselective (1,3 → 1,3) isomerization of (1,3)-diene. The reaction conditions are mild and easy to apply and can be applied to a wide range of substances, with an excellent yield and selectivity (90:10). It is evident from the crystal structures that the cause of regioselectivity for the isomerization of 1,3-diene may not be limited to 1,3-allylic strains; CH-π interaction may also play a vital role. Computational studies suggest that this regioselective photoisomerization is a thermodynamically feasible process and requires the accumulation of spin density on the modified double bond for the transformation to occur.