Nitrogen configuration determined by X‐ray analysis on an homogeneous series of 3‐Indolinones

The X‐ray diffraction analyses of 2‐methyl‐2‐phenylindolin‐3‐one 1 , 1,2‐dimethyl‐2‐phenylindolin‐3‐one 2 , 1‐hydroxy‐2‐methyl‐2‐phenylindolin‐3‐one 3 and 1‐methoxy‐2‐methyl‐2‐phenylindolin‐3‐one 4 have been carried out and the structural data were compared with those of 1‐oxyl‐2‐methyl‐2‐phenylindolin‐3‐one 5 . The results demonstrate that only compounds 2 and 5 show planar trigonal geometry which is coplanar with the conjugated benzene ring of the indolinic nucleus, whereas compounds 3 and 4 show a marked pyramidality of the nitrogen. Even if compound 1 shows a certain pyramidality of the nitrogen, it has been considered similar to compound 2 . The reactivity of all studied compounds fit the structural data.