Dennis Vogelsang

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.

Decreasing Side Products and Increasing Selectivity in the Tandem Hydroformylation/Acyloin Reaction

A highly selective catalyst system was developed for the recently discovered tandem hydroformylation/acyloin reaction by systematic investigations and changes of reaction conditions. This new catalyst system is characterized by an excellent selectivity of the desired reaction pathway with negligible amounts of side products. A successful application of the tandem hydroformylation/acyloin reaction to a variety of olefins is enabled with comparable excellent selectivities up to >99 % for the first and second reaction step, therefore a general synthesis for the conversion of olefins into acyloins is found. Furthermore, very good to excellent yields for the intermediates and final acyloin products were observed within two catalysed reactions in one preparative step. The acyloin product was applied as a nonpolar precursor for surfactants. After attaching a polar head group to the acyloin and determination of tensiometric data, the molecule showed industrial relevant surface‐active properties.

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 %.

A general and efficient method for the palladium-catalysed conversion of allylic alcohols into their corresponding dienes

A general method was established, converting a broad range of allylic alcohols directly and quantitatively into their corresponding dienes. The developed protocol allows the direct use of allylic alcohols, circumventing the need for their derivatisation into more reactive precursors, thereby minimising waste production with water as the sole co-product.

Homogeneously Catalyzed 1,3‐Diene Functionalization – A Success Story from Laboratory to Miniplant Scale

For many years, the efficient use of resources has been a major and permanent challenge for the chemical industry. The implementation of alternative resources such as renewables and carbon dioxide has been a subject of considerable discussion, but also the more efficient use of long known bulk chemicals is of great interest. Among them, 1,3‐dienes such as 1,3‐butadiene from the C4 cut of the naphtha cracker as well as isoprene, piperylene and cyclopentadiene from the corresponding C5 section are important substrates. These dienes are presently employed in various markets, with the greatest importance being in the production of polymers and copolymers. However, homogeneous transition metal catalysis has proven to be a versatile tool to functionalize these important 1,3‐dienes to low molecular weight fine chemicals by introducing, for example, nitrogen, oxygen or silicon. Hence, an upgraded use of the corresponding products as agrochemicals, pharmaceuticals, fragrances or special detergents is close at hand. The main approaches in the topic of homogeneous functionalization reactions of the industrially relevant 1,3‐dienes will be summarized and discussed within the present article. Besides that, novel applications including renewable 1,3‐dienes, for example β‐myrcene and β‐farnesene, as well as the application of CO2 in telomerization, will be critically discussed.