1,3-Pentadiene hydroformylation

The chemo- and regioselectivities of hydroformylation reactions of open chain, conjugated dienes using the usual catalyst are, in most cases, rather low [36]. The rhodium/ mesitylene co-condensate (catalyst A), in the presence of bis(diphenylphosphino)ethane, DPPE, catalyses the hydroformylation of 1,3-butadiene, isoprene, and E,Z)-, 3-pentadiene to the corresponding p,y-unsaturated monoaldehydes, with unusually high chemo- and regioselectivities (Scheme 17). 

Since conjugated dienes form stable rc-allyl complexes with [Co(CO)4]2, they undergo hydroformylation very slowly to give saturated monoaldehydes in low yields.8 Mixtures of mono- and dialdehydes are usually formed in rhodium-catalyzed hydroformylations.71 72 Saturated monoaldehydes were isolated, however, when 1,3-butadiene and 1,3-pentadiene were hydroformylated in the presence of rhodium dioxide.70... 

The hydroformylation of conjugated dienes such as 1,3-butadiene, isoprene, and 1,3-pentadiene gives mixtures of regioisomers, isomerized aldehydes, and dialdehydes depending on the conditions and catalysts used. The reaction of 1,3-butadiene provides 1,6-hexanedial and has relevance to nylon produc-The reaction of 1,3-cyclohexadiene catalyzed by a rhodium complex... 

Table 13-13 Plackett-Burman plan for the hydroformylation of 1,3-pentadiene ...

In 2015, Behr s group investigated the hydroformylation of 1,3-pentadiene (piperylene) (Scheme 4.12) [79]. With a Xantphos-based rhodium catalyst, mainly /Z-2-methylpent-2-enal was obtained. By running the reaction in... 

---