Hydrolytic cyclization of 2-acyl-(2-cyanoethyl) succinates (Ib, c) was found to give 2, 3, 3a, 4, 5, 6-hexahydroindole-2, 6-diones (IIb, c), which readily yielded 6-hydroxyoxindoles (III) by dehydrogenation. Four-step synthesis of the erythrinane skeleton from methyl acetoacetate via IIb is also described.
