0 0 1 observed that these bright yellow, orange, or red com- pounds were bleached in base, but no products could be characterized. Isatogens, which contain a keto nitrone function similar to that in 1, were reported to add ethyl cyanoacetate under Knoevenagel conditions.2 We decided to attempt a similar reaction with a derivative of 1 containing no base-sensitive alkyl groups. When ester 2l was treated with ethyl cyan- oacetate in the presence of an equivalent of ...
