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UNEXPECTED PYRYLIUM TO PYRYLIUM DOMINO TRANSFORMATION. SYNTHESIS OF PYRANO[3,4-c]PYRAN-7-IUM CATION AND ITS RECYCLIZATION TO 2,7-NAPHTHYRIDINE DERIVATIVE

Konstantin F. Suzdalev, Alina V. Krachkovskaya, Mikhail E. Kletskii, Oleg N. Burov, Artem V. Tatarov, Sergey V. Kurbatov
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Abstract


4-Ethyl-3-formyl-2,6-diphenylpyrylium perchlorate was obtained from 2,6-diphenylpyrylium perchlorate in three steps. Its reaction with triethyl orthoformate was accompanied by rearrangement of the initial pyrylium ring and led to pyrano[3,4-c]pyran-7-ium perchlorate system through a domino process involving ethanol addition-elimination. A plausible mechanism of the reaction is suggested on the basis of DFT quantum-chemical calculations. Reaction of the obtained pyrano[3,4-c]pyran-7-ium perchlorate with ammonium acetate led to a 2,7-naphthyridine derivative without a skeletal rearrangement.

 


Keywords


naphthyridine; pyrylium salts; triethyl orthoformate; domino process; recyclization

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Latvian Institute of Organic Synthesis - Aizkraukles iela, 21, Riga, LV-1006, Latvia - hgs@osi.lv