1403878-94-3Relevant articles and documents
Spiroketal-based phosphorus ligands for highly regioselective hydroformylation of terminal and internal olefins
Jia, Xiaofei,Wang, Zheng,Xia, Chungu,Ding, Kuiling
, p. 15288 - 15295 (2013/01/15)
A new class of bidentate phosphoramidite ligands, based on a spiroketal backbone, has been developed for the rhodium-catalyzed hydroformylation reactions. A range of short- and long-chain olefins, were found amenable to the protocol, affording high catalytic activity and excellent regioselectivity for the linear aldehydes. Under the optimized reaction conditions, a turnover number (TON) of up to 2.3×104 and linear to branched ratio (l/b) of up to 174.4 were obtained in the RhI-catalyzed hydroformylation of terminal olefins. Remarkably, the catalysts were also found to be efficient in the isomerization-hydroformylation of some internal olefins, to regioselectively afford the linear aldehydes with TON values of up to 2.0×104 and l/b ratios in the range of 23.4-30.6. X-ray crystallographic analysis revealed the cis coordination of the ligand in the precatalyst [Rh(3 d)(acac)], whereas NMR and IR studies on the catalytically active hydride complex [HRh(CO)2(3 d)] suggested an eq-eq coordination of the ligand in the species. Spiro-spine! The effect of a spiro backbone was observed in the rhodium-catalyzed hydroformylation of terminal and internal olefins. High activity and excellent regioselectivity for the formation of linear aldehydes was realized in the case of the matched stereochemistry of the ligand (see scheme). It was found that the spiroketal is superior to biphenyl as the backbone of the ligand in terms of the regioselectivity of hydroformylation. Copyright
