Pure Appl. Chem., 2012, Vol. 84, No. 8, pp. 1759-1769
Published online 2012-02-03
Catalytic asymmetric synthesis using chirality‑switchable helical polymer as a chiral ligand
Single-handed PQXphos, i.e., helical poly(quinoxaline-2,3-diyl)s bearing diarylphosphino pendant groups, served as remarkable chiral ligands
in palladium-catalyzed asymmetric
hydrosilylation of styrenes and asymmetric
biaryl synthesis by Suzuki–Miyaura coupling
, affording up to 98 % enantiomeric excess (e.e.) in both reactions. A palladium complex of high-molecular-weight variant (1000mer) of PQXphos could be reused eight times by virtue of the formation of an insoluble polymer complex. PQXphos underwent solvent-dependent inversion
of the helical sense, enabling production of either of two enantiomeric products using a single PQXphos.
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