Chemistry of Heterocyclic Compounds, Vol. 45, No. 5, 2009 INVESTIGATION OF THE STRUCTURE AND PREDICTION OF THE BIOLOGICAL ACTIVITY OF 1,3-BIS(3-CYANO-6,6-DIMETHYL- 2-OXO-5,6-DIHYDRO-2H-PYRAN-4-YL)- 2-(4-METHOXYPHENYL)PROPANE* M. Fleisher 1 **, S. Belyakov 1 , D. Jansone 1 , V. Poroikov 2 , L. Leite 1 , and E. Lukevics 1 Single crystals of 1,3-bis(3-cyano-6,6-dimethyl-2-oxo-5,6-dihydro-2H-pyran-4-yl)-2-(4-methoxyphenyl)- propane were prepared, and an X-ray crystallographic analysis was performed. The compound has a molecular structure belonging to the C 1 symmetry group. The heterocyclic rings are in a distorted half- chair conformation. The crystal packing is formed by centrosymmetric dimers, in which the heterocycles turned toward the inversion center are antiparallel. The biological activity of the compound was predicted by the PASS computer system. Keywords: 1,3-bis(3-cyano-6,6-dimethyl-2-oxo-5,6-dihydro-2H-pyran-4-yl)-2-(4-methoxyphenyl)- propane, X-ray structural analysis, PM6, PASS. In a continuation of our investigations in the search for new physiologically active compounds of the δ-lactone class the reaction of 3-cyano-4,6,6-trimethyl-5,6-dihydro-2-pyranone with 4-methoxybenzaldehyde in ethanol in the presence of catalytic amounts of NaOH was realized. It was found that together with the expected crotonic condensation product 3-cyano-6,6-dimethyl-2-oxo-5,6-dihydro-4-[2-(4-methoxyphenyl)vinyl]- 2H-pyran a compound of the Michael adduct type 1,3-bis(3-cyano-6,6-dimethyl-2-oxo-5,6-dihydro-2H-pyran- 4-yl)-2-(4-methoxyphenyl)propane (1) is also formed. The synthesized compounds were identified on the basis of spectral data and elemental analysis [1]. Quantum-chemical investigation of the reaction showed that both products are produced from a common protonated intermediate and the difference in the mechanisms of their formation arises from the regioselectivity of the stage involving interaction of the HetCH 2 − carbanion with the intermediate. In the case where attack by the carbanion is directed at the α-carbon atom of the double bond in the intermediate a _______ * Dedicated to Highly Respected Academician Andris Strakovs in connection with his jubilee. ** To whom correspondence should be addressed, e-mail: misha@osi.lv. 1 Latvian Institute of Organic Synthesis, Riga LV-1006, Latvia. 2 V. N. Orekhovich Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow 119121, Russia; e-mail: vladimirporoikov@ibmc.msk.ru. __________________________________________________________________________________________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 680-685, May, 2009. Original article submitted March 12, 2009. 0009-3122/09/4505-0531©2009 Springer Science+Business Media, Inc. 531