Production of 5-alkoxyoxazoles useful as vitamin B6 intermediates comprises heating an alpha-isocyano alkanoate ester in the presence of a high molecular weight amine

摘要

Production of 5-alkoxyoxazoles (I) comprises heating an alpha -isocyano alkanoate ester (II) at a temperature above 80 [deg] C in the presence of an tertiary amine with a molecular weight above 185. Production of 5-alkoxyoxazoles of formula (I) comprises heating an alpha -isocyano alkanoate ester of formula (II) at a temperature above 80 [deg] C in the presence of an amine of formula NR5R6R7 with a molecular weight above 185. [Image] R1optionally substituted 1-6C alkyl; R2H or optionally substituted 1-6C alkyl; R5-R7optionally substituted 1-9C alkyl or 5-7C cycloalkyl; or two of R5-R7optionally substituted (un)saturated heterocycle. An independent claim is also included for production of pyridoxine derivatives of formula (IX) by: (1) esterifying an amino acid of formula (III); (2) converting the ester to a N-formyl derivative of formula (V); (3) converting this to (II) and thence 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 this to (IX) by acid treatment and deprotection. [Image] R3, R4protecting groups.