Abstract
A series of novel C2-symmetric bis(thiazoline) ligands with a diphenylamine backbone as a linkage between two thiazoline rings were synthesized by the use of the simple reagent phosphorus pentasulfide. Their application in the catalytic asymmetric Henry reaction of α-keto esters was investigated with comparison to the corresponding bis(oxazoline) ligands. Cu(II)-bis(oxazoline) complexes furnished moderate enantioselectivities (up to 60% ee), while Cu(II)-bis(thiazoline) complexes gave higher enantioselectivities (up to 70% ee) with neat nitromethane. The enantioselectivity was improved when a halogenated solvent, such as CH2Cl2 was used (up to 82% ee), but the yield obtained lower than that in neat reactions.
Original language | English |
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Pages (from-to) | 3433-3441 |
Number of pages | 9 |
Journal | Tetrahedron Asymmetry |
Volume | 15 |
Issue number | 21 |
DOIs | |
Publication status | Published - 1 Nov 2004 |
Externally published | Yes |