CLEANING PRECURSOR COMPOUND BY CRYSTALLISATION Russian patent published in 2016 - IPC C07B59/00 C07C227/18 C07C269/06 C07C303/28 

FIELD: treatment.

SUBSTANCE: invention relates to a method of producing precursors for radiopharmaceutical preparations used in positron emission tomography. More specifically invention relates to a method of producing a compound of formula I, in which R¹ represents a C_1-5alkyl group with a straight or branched chain; R² represents an amino protective group; v is an integer from 0 to 4; X is a leaving group selected from halogen or a -O-SO₂-R³ group, where R³ represents a halogen, C_1-10alkyl with a straight chain or branched chain, C_1-10haloalkyl with a straight chain or branched chain and C_6-10aryl. Method comprises (a) debenzylation of a compound of formula Ia, where R¹¹, R¹² and w are as defined for R¹, R² and v, respectively, in formula I; (b) crystallising reaction mixture of step (a) to obtain a purified compound of formula Ib, wherein R²¹, R²² and x are as defined for R¹, R² and v, respectively, in formula I; (C) converting purified compound of formula Ib obtained in step (b), a compound of formula I by reaction with a suitable form of X, where X is as defined for formula I. Method enables to increase yield of target compound as well as to achieve certain enrichment for syn-isomer during crystallisation.

EFFECT: invention also relates to a method for producing a compound of formula II using a method for producing a compound of formula I.

19 cl, 2 ex