Stereodivergent 3,4-Hydroalkoxylation of 1,3-Dienes Via Dual Photo and Copper Catalysis

We developed a photocatalytic copper-catalyzed stereodivergent 3,4-hydroalkoxylation of 1,3-dienes. By simply controlling reaction time, this protocol selectively affords either <i>E</i>- or <i>Z</i>-allylic ethers in moderate to excellent yields with high stereoselectivity (up to >20/1). The transformation demonstrates remarkable scalability, maintaining excellent stereocontrol even at gram-scale operations. Preliminary mechanistic studies reveal: (1) initial SET reduction generates key diene radical anion intermediates, (2) a synergistic photoredox/copper catalytic manifold directs <i>E</i>-selectivity, and (3) prolonged irradiation induces EnT-mediated photoisomerization to the <i>Z</i>-products.