Rhodium-catalyzed hydroformylation of internal alkenes

Beller et al. used NAPHOS 27, a BISBI analog backbone, substituted with 3,5-bistrifluoromethylphenyl groups as the ligand in rhodium-catalyzed hydroformylation of internal alkenes and obtained high selectivities to the linear product. 

Fuchs E, Keller M, Breit B (2006) Phosphabarrelenes as ligands in rhodium-catalyzed hydroformylation of internal alkenes essentially free of alkene isomerization. Chem Eur J... 

Phosphites have been extensively studied for their use as ligands in rhodium-catalyzed hydroformylation (see Chapter 3). The first publication on the use ofphosphites is from Pruett and Smith, from Union Carbide [31]. The first exploitation of bulky monophosphites was reported by van Leeuwen and Roobeek [32]. They found that very high rates can be obtained for internal and terminal alkenes, but selectivities were low for linear alkenes. The bulky phosphites not only gave higher rates than less bulky phosphites, but they are also more resistant to hydrolysis. Bryant and coworkers [33] introduced even more stable, bulky phosphites by the... 

The cobalt-catalyzed reaction of carbon monoxide and hydrogen with an alkene, hydroformylation, is an extremely important industrial process, but it occurs under vigorous conditions (200-400 bar, 150-200 °C) and is not a particularly selective reaction. In the presence of ligand-modified rhodium catalysts, however, hydroformylation can be carried out under extremely mild conditions (1 bar, 25 C). The catalytic activity of such rhodium complexes is in fact lO -Ky times greater than that of cobalt complexes and side reactions, such as hydrogenation, are significantly reduced. The reactivity of alkenes in hydroformylation follows a similar pattern to that observed in other carbonylation reactions, i.e. linear terminal alkenes react more readily than linear internal alkenes, which in turn are more reactive than branched... 

Internal alkenes. Dibenzophosphole- and phenoxaphosphino substituted xantphos ligands 42 and 43 were reported by van der Veen et al. [58, 59] (Figure 17). They show a high activity and selectivity in the rhodium catalyzed hnear hydroformylation of 1-octene (l b = > 60). More importantly, hgands 42 and 43 exhibit an unprecedented high activity and selectivity in the hydroformylation oftrans 2- and 4-octene to linear nonanal. 

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