Unprecedented reactivity of 5-substituted 3-hydroxy-1,2,3,4-tetrahydroquinoline-2,4-diones with ethyl (triphenylphosphoranylidene)acetate

3,5,8-Trisubstituted 3-hydroxy-1,2,3,4-tetrahydroquinoline-2,4-diones (3) r eacted with ethyl (triphenylphosphoranylidene)acetate (4) to yield several products. The major products, 4,7-disubstituted 1,3-dihydro-3-phenylacetoxy -2H-indol-2-ones (5) and (11), were formed via the molecular rearrangement of 3, catalyzed by the strongly basic Wittig reagent. The Wittig reaction a t the lactam group of 3, resulting in 2-ethoxycarbonylmethylene derivatives , can be explained by the poor reactivity of the sterically hindered 4-oxo group. Under acid catalysis, the Wittig reaction proceeded at the hindered 4-oxo group as well. A series of minor products were also obtained through the Wittig reaction of 3. A reaction mechanism of the molecular rearrangeme nt of substances (3) is proposed.