Modular synthesis of trisubstituted olefins and 1,3-dienes from renewable alcohols via ligand-enabled nickel...

Olefins are fundamental functional groups and of substantial commercial importance across a broad range of value-added chemicals. Their production from biomass-derived alcohols remains a longstanding goal, while the selective synthesis of trisubstituted olefins presents a formidable challenge that demands precise catalytic control to suppress undesired product formation. Herein, we demonstrate sequential cross-coupling/isomerization and cross-coupling/dehydrogenation of two different alcohols leading to stereoselective synthesis of trisubstituted olefins (27 examples; E/Z up to 98:2) and 1,3-dienes (23 examples; E/Z > 20:1) using a commercially available nickel catalyst enabled by ligand control. Late-stage functionalization using DL-galactose, α-tocopherol and post-product modification to a tamoxifen analogue and polyaromatic hydrocarbon highlight the significance of our developed method. Preliminary mechanistic studies indicate that alcohol dehydrogenation to the corresponding aldehyde is the rate-determining step (P_H/P_D = 4.3). Detailed mechanistic studies and deuterium labelling experiments support an underlying DCR (dehydrogenation-condensation-rehydrogenation) approach, followed by stereo-selective isomerization or dehydrogenation enabled by nickel.