Acid-catalysed rearrangements in the aryliminoindoline series. Part I. Crystal and molecular structures of 1-ethyl-2-(1-ethyl-2-phenylindol-3yl)-2-phenyl-3-phenyliminoindoline and 1-ethyl-3-(1-ethyl-2-phenylindol-3-yl)-3-phenyl-2-phenyliminoindoline

Abstract

Heating an ethanol–hydrochloric acid solution of 1-alkyl-2-(1-alkyl-2-phenylindol-3-yl)-3-arylimino-2-phenylindolines leads to rearrangements to 1-alkyl-3-(1-alkyl-2-phenylindol-3-yl)-2-phenylimino-3-phenylindolines anu to 3,3′-bi-indolyls and hydrolysis. The crystal structure of 1-ethyl-2-(1-ethyl-2-phenylindol-3-yl)-2phenyl-3-phenyliminoindoline(Vb) and of 1-ethyl-3-(1-ethyl-2-phenylindol-3-yl)-3-phenyl-2-phenyliminoindoline(IXb) were determined by direct methods from 4 420 and 5 469 independent reflections and refined by leastsquares to R 0.043 and 0.071. A mechanism for the rearrangements is suggested on the basis of the results of X-ray analysis and spectroscopic data.