An Unexpected α-Oxidation of Cyclic Ketones with 1,4-Benzoquinone by Enol Catalysis.

The first direct and asymmetric α-aryloxylation of cyclic ketones via enol catalysis has been achieved using quinones as the reaction partners. Catalytic amounts of a phosphoric acid promote the exclusive formation of α,α-disubstituted ketones from the corresponding α-substituted ketones in good yields and enantioselectivities (up to 96.5:3.

Synthesis of polycyclic spiroindolines by highly diastereoselective interrupted Ugi cascade reactions of 3-(2-isocyanoethyl)indoles.

We report a highly diastereoselective interrupted Ugi reaction to construct a broad range of structurally congested and stereochemically complex spiroindolines from tryptamine-derived isocyanides. The reaction is facilitated by using fluorinated alcohols (TFE or HFIP) as solvents and tolerates a broad range of amines, aldehydes and 2-isocyanoethylindoles to give polycyclic products in moderate to excellent yields.