Synthesis of 3-trifluoromethylated 1,3-butadienes via a Pd(0)-catalyzed fluorinated Heck reaction
1,3-Butadienes play a key role in modern synthetic chemistry and biochemistry because they are well-known precursors for the synthesis of retinoids. A new and efficient synthesis of 3-trifluoromethylated 1,3-butadienes via Pd(0)-catalyzed fluorinated Heck reaction is described. Without additive, 2-bromo-3,3,3-trifluoropropene, an abundant and ozone friendly CF3 building block with acrylamides afforded 3-trifluoromethylated 1,3-butadienes in good to excellent yields with high regioselectivity and s-trans/s-cis ratios under mild conditions. Inspried by the concept of space-time yield for contineous reaction, the average space-time yield calculated shows that all the reactions far exceed 1 g/(gcat.*h), which is high enough for further scale-up, suggesting low catalyst required and small reactor matched. .