Highly Enantioselective Catalytic Kinetic Resolution of α-Branched Aldehydes through Formal Cycloaddition with Homophthalic Anhydrides.

A new catalytic methodology was developed to promote an efficient one-pot kinetic resolution of racemic aldehydes with selectivity (s*) of up to 91 (99:1 d.r., >99 % ee) in a cycloaddition reaction with enolizable anhydrides to afford dihydroisocoumarin products (a core prevalent in natural products and molecules of medicinal interest) containing three contiguous stereocentres.

Catalytic Asymmetric Cycloadditions between Aldehydes and Enolizable Anhydrides: cis-Selective Dihydroisocoumarin Formation.

In the presence of a trityl-substituted cinchona alkaloid-based catalyst, homophthalic, aryl succinic, and glutaconic anhydride derivatives reacted with aromatic and aliphatic aldehydes to produce cis-lactones in up to 90:10 dr and 99% ee. A DFT study has shown how the catalyst is uniquely able to bring about the opposite sense of diastereocontrol to that usually observed.