From Carboxytelomerization of 1,3-Butadiene to Linear α,ω-C10 -Diester Combinatoric Approaches for an Efficient Synthetic Route.

Two novel reaction pathways were tested to synthesize the linear α,ω-C10 -diester exclusively from three basic reagents: 1,3-butadiene, carbon monoxide and methanol. Therefore, carboxytelomerization of 1,3-butadiene and methanol was merged with methoxycarbonylation in two different ways to obtain highly linear C10 -diester. Through a palladium-based and -assisted tandem catalytic system, 22 % yield of the desired C10 -diester was obtained without isolating the intermediates. Subsequently, the limitations of the novel assisted tandem catalytic concept were uncovered and based on that, a two-step reaction regime was established. By optimization of the carboxytelomerization, the C9 -monoester as intermediate could be formed in nearly quantitative yields and excellent linearity. In a second reaction step, the isolated monoester was successfully converted by methoxycarbonylation into the desired linear C10 -diester in overall yields up to 84 %.

Direct Synthesis of an α,ω-Diester from 2,7-Octadienol as Bulk Feedstock in Three Tandem Catalytic Steps.

A new tandem catalytic process was designed and developed as a tool for the direct conversion of the widely available feedstock 2,7-octadienol into an α,ω-diester. This innovative auto-tandem catalysis is atom efficient and consists of three consecutive palladium-catalysed reactions: ether formation, ether carbonylation and alkoxycarbonylation. By using the design of experiments (DoE) approach, significant parameters were determined and the yield of the desired α,ω-diester was optimised. Model substrates allowed deeper insight into the progress of the reaction to be gained and, as a result, the reaction sequence was uncovered. Furthermore, by simply applying other ligands, a different reaction path was followed, allowing other, new tandem catalytic sequences to be explored and enabling new compounds to be obtained.