Lewis acid enhancement by hydrogen-bond donors for asymmetric catalysis

Lewis acid enhancement by hydrogen-bond donors for asymmetric catalysisBySteven M. Banik,Anna Levina,Alan M. Hyde,Eric N. JacobsenScience10 Nov 2017 : 761-764A chiral amide activates a silicon-based Lewis acid for joint asymmetric catalysis.Molecular catalysts with two closely spaced nitrogen-hydrogen groups can act like a tweezer, activating a carbon center by latching onto a leaving group through double hydrogen bonding and then pulling it away. In the resultant ion pair, the shape of the catalyst can bias an ensuing reaction to favor just one of two possible mirror-image products. Baniket al. used this motif to activate a Lewis acid cocatalyst, pulling a leaving group off silicon instead of carbon (see the Perspective by Mattson). The combined pair of catalysts is more effective for reactions such as asymmetric cycloadditions that involve weaker leaving groups on carbon.

Source: Organometallic Current - November 10, 2017 Category: Chemistry Tags: Asymmetric Lewis acid catalysis Source Type: blogs