Asymmetric Intramolecular Crossed Aldehyde-Ketone Benzoin Cyclization

Significance Here the authors report an enantio­selective intramolecular aldehyde-ketone benzoin cyclization. Rovis’ aminoindanol-derived triazolium salt 1 ( J . Am . Chem . Soc . 2005 , 127 , 6284-6289) in combination with DBU has been found to be effective for the reaction. With 10-25 mol% of 1 , moderate to high yields (44-91%) and enantio­selectivities (39-99%) are obtained for a wide variety of substrates.