Highly Efficient and Linear-Selective Hydroformylation of Allyl Acetate Under Mild Conditions Regulated by Additives

1,4-Butanediol, an important chemical raw material, especially as the monomer of engineering plastic polyethylene terephthalate (PBT), plays a pivotal role in contemporary chemicals. A promising parallel approach is the linear-selective hydroformylation of inexpensive allyl acetate, which is economical yet challenging. Herein, we describe an atom-economic approach characterized by high selectivity for synthesizing 4-oxobutyl acetate through rhodium-catalyzed hydroformylation using allyl acetate. This protocol affords the intermediate of valuable 1,4-butanediol in excellent yield (up to 95%) and exhibits excellent regioselectivity (linear/branched up to 164) under mild conditions (60 °C, 10 bar of syngas), effectively minimizing the formation of decomposed byproducts. The success of this protocol hinges on the use of a "Rh/POP-type ligand" in combination with either acetic acid or bulky anionic salts as additives. Preliminary mechanism studies show that the use of CH₃COOH facilitates the formation of a tridentate κ³-P,O,P-coordination, which prevents the coordination of carbonyl with the Rh center, leading to the relatively high linear selectivity of 4-oxobutyl acetate. Furthermore, the successful application of this protocol in synthesizing 4-oxobutyl acetate at a scale of 3.8 g, employing low Rh-loading (0.05 mol%), highlights its potential for industrial applications.