Water soluble lanthanoid benzoate complexes for the kinetic separation of cis/trans-limonene oxide

A new class of water soluble, environmentally friendly, lanthanoid 3,5-diacetamidobenzoate complexes (Ln = La, Gd, Yb) have been synthesized. The La and Gd complexes selectively catalyse hydrolysis of the cis-isomer of limonene oxide allowing for the separation of the trans-isomer (>98:2 dr) in up to 74% yield. Comparative studies with the corresponding chlorides and triflates reveal the lanthanoid benzoate complexes to be more active than the chlorides, but less active, though more selective, than the triflates.

Figure optionsDownload as PowerPoint slide

(+)-trans-Limonene oxideC10H16OEe 98%[α]D = +78 (neat)Source of chirality: kinetic separation of commercially available diastereoisomersAbsolute configuration: (1S,2R,4R)