C2 Symmetric chiral diphosphite ligands

Optically active diols are useful building blocks for the synthesis of chiral diphosphite ligands. Chiral diphosphites based on commercially available optically active 1,2 and 1,4-diols, 1,2 5,5-diisopropylidene-D-maiinitol, L-a,a,a,a-tetramethyl-l,3-dioxalan-4,5-dimethanol and L-diethyl tartrate, 1-3, were first used in the asymmetric hydroformylation of styrene [17]. 

Ee s reached 20 % and regioselectivities to the branched aldehyde were high with the most bulky ligand under mild reaction conditions. The less bulky and more flexible diphosphites hardly produce enantioselectivity. 

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