METHODS OF SYNTHESIS OF PYRIDINE-2-CARBOXALDEHYDE THIOSEMICARBAZONES AND INTERMEDIATE PYRIDINE-2-CARBOXALDEHYDES Russian patent published in 2003 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to the improved method of synthesis of compounds of the formula (I) where R⁴ means H or CH₃ involving interaction of compound of the formula (2-C) where R¹ means group NO₂ with thiosemicarbazide to yield thiosemicarbazone of the formula (TS1) followed by reduction of synthesized compound. Invention proposes also method of synthesis of thiosemicarbazone of the formula (TS2) involving interaction of compound of the formula (2-C) where R¹ means group NHP with thiosemicarbazide. Invention proposes also methods of synthesis of intermediate compounds of the formula (2-C) where R¹ means NO₂,NH₂, NHP, NPP, N₃ or CO₂R²; P and P mean protective groups; R² means C₁-C₃-alkyl; R⁴ means H or CH_3/ and compounds of the formula (4) . Proposed methods of synthesis of pyridine-2-carboxaldehyde thiosemi-carbazones allows to increase the yield of end compounds up to 30% from easily available substances. EFFECT: improved methods of synthesis, increased yield. 21 cl, 3 dwg, 1 tbl