METHOD OF PREPARING TRANS-6-[SUBSTITUTED PYRROL-1- YL)ALKYL]PYRAN-2-ON DERIVATIVES AND THEIR DIHYDROXY-CONTAINING ACIDS AND SALTS, HYDROXY-, 1,3-DIOXAN- OR PYRROLE-CONTAINING CARBOXYLIC ACIDS AS INTERMEDIATES FOR PREPARING SAID PYRAN-2-ON DERIVATIVES Russian patent published in 1999 - IPC

FIELD: organic synthesis. SUBSTANCE: trans-6- [substituted pyrrol-1-yl)alkyl]pyran-2-on derivatives having general formula I: (I), wherein R¹ is phenyl optionally substituted by fluorine, bromine, or chlorine; R² and R³ are hydrogen, alkyl, phenyl or radical -CONR⁵R⁶, in which R⁵ and R⁶ are hydrogen, alkyl, or phenyl optionally substituted by fluorine, chlorine, or bromine; and R⁴ is C_1-6- alkyl, are prepared with compound of formula II () with compound of formula III () followed by interaction of resulting intermediate having formula IV (NC-CH₂CH-CH₂-CO-CH₂-CONR⁸R⁹) with R102

BOCH₃ or R102B and then with borane in solvent. Resulting compound NC-CH₂CH-CH₂-CO-CH₂-CONR⁸R⁹ is brought into reaction with reagent R¹¹R¹²C(OCH₃)₂ or R¹¹R¹²CO under acid conditions. Resulting ketal having formula V () is hydrogenated and brought into reaction with compound R¹COCHR²CHR³COR⁴ to give intermediate VI (), which is treated with acid in solvent and hydrolyzed with base to give intermediate that, after neutralization with acid and dissolution in solvent with simultaneous removal of water, is converted into final product. EFFECT: increased yield and reduced expenses on reagents. 14 cl, 2 dwg, 6 ex