Process for the preparation of 5-alkoxy-oxazoles as well as of pyridoxines

摘要

Production of 5-alkoxy oxazoles (I) comprises heating an alkyl alpha -isocyanoalkanoate ester (II) at a temperature above 80 degrees C in the presence of an auxiliary agent and simultaneously separating the product from the reaction mixture. Production of 5-alkoxy oxazoles of formula (I) comprises heating an alkyl alpha -isocyanoalkanoate ester of formula (II) at a temperature above 80 degrees C in the presence of an auxiliary agent and simultaneously separating the product from the reaction mixture. R1 = optionally substituted 1-6C alkyl; R2 = H or optionally substituted 1-6C alkyl. An Independent claim is also included for a process for producing pyridoxine derivatives of formula (IX), comprising: (1) converting an amino acid of formula (III) to an ester of formula (IV); (2) converting (IV) to a formamido ester of formula (IV); (3) converting (IV) to (II), converting (II) to (I) as above; (4) reacting (I) with a protected diol of formula (VI) to form a Diels-Alder adduct of formula (VII); and (5) converting (VII) to (IX) by acid treatment and deprotection. R3, R4 = protecting groups or together form a protecting group.