Patent ID: 6559311
Filing Date: 2003-05-06
Classification: C07D

Abstract:
A process for preparing a novel Tinuvin P-Hindred Amine Light Stabilizer derivative of the general formula (I) wherein R1 is hydrogen, halogen, C1 to C12 alkyl, alkoxy (linear and branched), R2 is hydrogen, C1-C8 alkyl, cyclopentyl, cyclohexyl or cumyl, R3 is hydrogen, C1-C4 alkyl, R4 is methyl or ethyl, R5 is C1-C8 alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is O, NH, C1-C8 alkyloxy and alkylamino (linear or branched) comprising dissolving a compound of formula (II) wherein R1 is hydrogen, halogen, C1 to C12 alkyl, alkoxy (linear and branched), R2 is hydrogen, C1-C8 alkyl, cyclopentyl, cyclohexyl or cumyl, with an organic base in a dry organic solvent under inert condition, agitating it initially for a period of 20-30 minutes followed by addition of an hydroxy protecting group and stirring the reaction mixture for 10-14 min under inert atmosphere, followed by evaporating the organic solvent and drying the residue, subsequently dissolving the residue in a low boiling organic solvent followed by filtering the insoluble mass and evaporating the solvent to obtain a compound having general formula (III) wherein R1 is hydrogen, halogen, C1 to C12 alkyl, alkoxy (linear and branched), R2 is hydrogen, R1-C8 alkyl, cyclopentyl, cyclohexyl or cumyl, and Y is tertbutyldimethylsilyl, tertbutyldiphenylsilyl, dimethylthexylsilyl, benzoyl, benzyl, and acetyl,dissolving compound of formula (III) in a dry organic solvent under inert condition and simultaneously dissolving compound of formula (IV) wherein R3 is hydrogen, C1-C4 alkyl, R4 is methyl, ethyl, R5 is C1-C8 alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is OH, NH2, C1-C8 alkyloxy and alkylamino (linear or branched) separately but in the same solvent and adding to it a dry metal hydride, agitating the solution for 30-60 minutes, cooling it to 4-8Â° C. and then adding the solution of compound of formula III gradually over a period of 30-60 minutes, agitating the reaction mixture for 2-4 hrs, followed by refluxing the same for 2-4 hrs, cooling the reaction mixture to room temperature and agitating for 4-6 hrs followed by evaporating the organic solvent under reduced pressure, dissolving the solid mass in water and extracting the product in an organic solvent through repeated extractions and evaporating the organic solvent to obtain a compound of formula (V) wherein R1 is hydrogen, halogen, C1 to C12 alkyl, alkoxy (linear and branched), R2 is hydrogen, C1-C8 alkyl, cyclopentyl, cyclohexyl or cumyl, R3 is hydrogen, C1-C4 alkyl, R4 is methyl or ethyl, R5 is C1-C8 alkyl, alkyl phenyl, alkoxy, acyl, cycloalkyl and allyl, X is O, NH, C1-C8 alkyloxy and alkylamino (linear or branched), Y is tertbutyldimethylsilyl, tertbutyldiphenylsilyl, dimethylthexylsilyl, benzoyl, benzyl, and acetyl,taking the compound (V) with a hydroxy deprotecting reagent and stirring the reaction mixture at room temperature for 1-3 hrs followed by addition of water and extracting the product in an organic solvent, drying the solvent with an anhydrous inorganic salt after neutralization with an inorganic base an evaporating the solvent to obtain the compound of formula I.