A Tetraphosphorus Ligand for Highly Regioselective Isomerization−Hydroformylation of Internal Olefins

Abstract

A new pyrrole-based tetraphosphorus ligand capable of forming multiple chelating modes has been prepared. Higher regioselectivity has been achieved in the rhodium-catalyzed isomerization-hydroformylations of internal olefins compared with its bisphosphorus analogue.

Rhodium-Biphephos-Catalyzed Tandem Isomerization–Hydroformylation of Oleonitrile

“…Rhodium-catalyzed tandem isomerization-hydroformylation of middle-chain alkenes (<10 C) has been widely studied over the last two decades, generally with bulky ligands [7,8]. Regioselectivities in the range l/b = 95:5-98:2 were obtained with 2-alkenes (e.g., 2-hexene, 2-octene) [9][10][11][12][13][14], while with 4-octene regioselectivities up to l/b = 89:11 were observed [15,16]. On the other hand, the hydroformylation of long-chain alkenes (>10 C), with a C=C bond in a deep internal position (>5 C away), remains poorly documented.…”

Applications of Rhodium-Catalyzed Hydroformylation in the Pharmaceutical, Agrochemical, and Fragrance Industries

“…Realistically, for more complex targets, any synthetic method must compete with a variety of other synthetic disconnections on factors such as cost, complexity, and waste treatment. A significant advantage of hydroformylation is perfect atom economy, and ligands developed within the past 20 years offer excellent regioselectivity [2][3][4], chemoselectivity, and functional group tolerance. For example, xantphos and biphephos ligands lead to high selectivity for linear aldehydes from terminal alkenes (Fig.…”

Synthesis and Application of Tetraphosphane Ligands in Rhodium‐Catalyzed Hydroformylation of Terminal Olefins: High Regioselectivity at High Temperature

“…[10] This multidentarity effect has also been observed in our previously developed pyrrole-based tetraphosphoramidite ligands for the regioselective hydroformylation of internal olefins, styrene and its derivatives, vinyl acetates, and dienes, which all show exceptionally high regioselectivity towards the formation of linear aldehydes. [11] The peculiar behavior of those ligands was ascribed to the large bite angle formed by coordination with the metal (nine-membered ring), the multiple coordination modes increase the concentration of the selective catalytic species, and the electron-withdrawing property of the N-pyrrolylphosphorus moiety. [7] Ligand 1 has similar coordination modes to those of the tetraphosphoramidite, but with more electron-rich phosphorus moieties.…”