Various acid-promoted reactions gave the desired products in high yields by passing a solution of reactants through a reaction column packed with polystyrene-bound super Brønsted acid (1) just once. Polar and nonpolar organic solvent-swellable 1 is much superior to Nafion® SAC-13 (2) as a Brønsted acid-loaded resin packed in the column.
Asymmetric reduction of aliphatic ketones and acyl silanes using chiral anti-pentane-2,4-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid
Aliphatic ketones were reduced to the corresponding secondaryalcohols by using anti-1,3-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid (DNBSA) in benzene at reflux. Addition of 1-octanethiol in that media improved the efficiency of the reduction. Asymmetric reduction of aliphatic ketones was performed by using chiral anti-pentane-2,4-diol, and highly asymmetric induction (up to >99%