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.

Catalytic asymmetric Tamura cycloadditions involving nitroalkenes.

The first examples of asymmetric Tamura cycloaddition reactions involving singly activated alkenes are reported. Homophthalic anhydride reacts with α-methyl nitrosytrenes in the presence of an alkaloid-based catalyst to generate fused bicyclic aromatic ketone products with three new stereocentres (which are susceptible to subsequent equilibration) in 12-99% ee. An unusual equilibration process which occurs in methanolic medium in the absence of a recognisable base via proton transfer at the α-carbon of an ester was investigated experimentally and computationally.

Enantioselective diamination with novel chiral hypervalent iodine catalysts.

Vicinal diamines constitute one the most important functional motif in organic chemistry because of its wide occurrence in a variety of biological and pharmaceutical molecules. We report an efficient metal-free, highly stereoselective intramolecular diamination using a novel chiral hypervalent iodine reagent together with its application as an efficient catalyst for the synthesis of diamines.

Highly stereoselective metal-free oxyaminations using chiral hypervalent iodine reagents.

The ring and I: hypervalent iodine compounds avoid the issues of toxicity or complicated ligands of many transition-metal-based systems. A highly enantioselective oxyamination of alkenes with N-sulfonyl ureas employing chiral, lactic acid-based hypervalent iodine reagents gives a facile synthesis of enantiomerically pure 2-arylproline derivatives for the first time.