METHOD OF PREPARING 3-PYRROLINE-2-CABOXYLIC ACID DERIVATIVES Russian patent published in 2003 - IPC

FIELD: organic synthesis. SUBSTANCE: invention relates to novel method for preparation of 3- pyrroline-2-caboxylic acid derivatives having general formula I: (I), where R¹ represents C1-C6-alkyloxycarbonyl and R² hydroxyl or C1-C4-alcoxy, or their ammonium salts, which involves base-mediated cleavage of sulfuric acid residue from compound II: (II), where R¹ and R² are as above, and R³ denotes C1- C6-alkyl, benzyl, trifluoromethyl, naphthyl, or phenyl optionally substituted by residue including methyl, nitro, or halogen, carried out in aprotic solvent and followed by (if necessary) converting resulting racemate, in the case of R² = C1-C4-alcoxy, into optically active acids and isolation of desired product in free state or in the form of ammonium salt. Above-mentioned base is selected from group including hydrides, bis-alkylsilylamides, sodium and potassium alcoholates. Method of preparing 3,4-dehydroproline derivatives of formula III: (III), wherein R¹ is as above and X denotes , by reaction of compound I with compound V: H₂N-CH₂-X, wherein X is specified above, is described. Ammonium salts of compound 1 are also disclosed. EFFECT: expanded synthetic possibilities in the pyrrol chemistry area. 8 cl, 8 ex