In most cases NMR spectroscopy serves to confirm the structure of estimated compounds,
to determine some configurations of already known molecules. But it is quite difficult to
establish the structure of an unknown compound with a complex construction.
Nevertheless, in some cases this can be done, even if the construction of such molecules
seems to be unreal.
Organic synthesis is fairly predictable. However, sometimes there are surprises when
instead of the expected products other compounds with unusual structures are obtained.
In this report, one of them will be presented.
The target product of reaction between indole-2,3-dione with methylacrylate (in absolute
DMFA with equimolar presence of NaH) should to be compound 2. But the main product of
the reaction was another compound. Following the data of the NMR analysis, it was
suggested that this is a mixture of two diastereomers 3. To confirm the expected structure,
dehydration was performed, which resulted in product 4, the structure of which was
confirmed by NMR spectra too. To determine the structure of described substances, various
NMR analyzes were applied (one-dimensional (1H, 13C, DEPT-90o and DEPT-135o) and twodimensional
homo-(1H/1H COSY-45o, 1H/1H NOESY) and heteronuclear (1H/13C HSQC and
HMBC)).The structure of the 4 was later confirmed by the data of X-ray analysis.

Acknowledgments
the authors are grateful for the funding offered by the National Agency for Research and
Development of the Republic of Moldova under the project 19.80012.80.07А.