Abstract
Asymmetric hetero Diels-Alder (HDA) reaction of highly reactive acyl nitroso intermediates are reported. Transient acyl nitroso compounds 2a'-c' are formed by Ru(II)- or Ir(I)-catalyzed hydrogen peroxide oxidation of hydroxamic acids 2a-c and are trapped in situ by the optically pure N-dienyl-L-pyroglutamates 1a-b to afford the corresponding diastereomeric adducts 3a-f and 4a-f up to 98% yield (70% de) and 72% de (70% yield) with complete regioselectivity at 0 degrees C to room temperature.