The absolute configuration of an inherently chiral phosphonatocavitand and its use toward the enantioselective recognition of l-adrenaline

An inherently chiral ABii diphosphonato cavitand (±)-4 bearing a single quinoxaline bridging moiety was synthesized and resolved by chiral HPLC. Its chiroptical properties were investigated and VCD experiments allowed the determination of its absolute configuration. Distinguishable diastereomeric complexes in solution with l-adrenaline were observed by 1H and 31P NMR together with a noticeable enantio-discrimination at 253 K (dr ∼2:1) in favor of the dextrorotatory cavitand (+)-4.

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(+)-ABii[(PhPO)2,Quinoxaline][(C11H23)4]C92H120N2O10P2Ee >99%[α]D25=+34 (c 0.59, CHCl3)tR = 10.51 min (Chiralpak IC, hexane/ethanol/chloroform 80/10/10, 1 ml/min)Absolute configuration (cS)Source of chirality: resolution