Plieninger (1) reported that the phenywdrazone of a-keto-y-butyrolactone (I), when subjected to the conditions appropriate for the Fischer indole synthesis (treatment with hydrogen chloride in glacial acetic acid at 900), rearranged to form a product for which the structure 11 was suggested. The latter substance yielded the indole III when heated in a mixture of glacial acetic acid and concentrated hydrochloric acid; it was regarded by Plieninger as representing an intermediate of a type which had been postulated to intervene in the course of the Fischer synthesis (2), but had not previously been demonstrated by isolation. In a more recent study (3), similar treatment of the phenylhydrazones of several l-Substituted-A-benzyl-2,3_dioxopyrrolidines (V) was found to lead to 3a-amino-8b-benzyl-l,3a,4,8btetrahydropyrrolo[3,1*-blindole-3(W)-ones (VIII). It seemed quite possible, therefore, that Plieninger's intermediate might be similarly constituted (as in formula IV); no spectroscopic characterization supporting structure II had been reported.
In agreement with Plieninger's findings, we found that the action of hydrogen chloride in acetic acid on a-keto-y-butyrolactone phenylhydrazone (I) (4) yielded a rearrangement product which retained both nitrogen atoms. (Calcd.