Direct Bifunctional Squaramide-CatalyzedAsymmetric N-Nitroso Aldol Reactionof Tertiary β-Carbonyl Esters

Enantioselective asymmetric N-nitrosoaldol reaction of tertiary β-carbonyl esters using thebifunctional squaramide organanocatalysts is described. These adductshave been obtained in moderate yields and with up to 98% ee.