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US 2003/0120082 A1Published application
Continuous preparation of substituted oxazoles
AssigneeBASF SE
InventorsHarald Rust, Kirsten Burkart, Tillmann Faust, Jochem Henkelmann, Christian Knoll, Andre Mohry, Alois Kindler
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Abstract
The present invention relates to a process for continuously preparing 5-alkoxy-substituted oxazoles, in particular for continuously preparing 4-methyl-5-alkoxy-substituted oxazoles and also a process for preparing pyridoxine derivatives.
Claims15
A process for continuously preparing 5-alkoxy-substituted oxazoles of the formula I
- 12
- where
- R1 is an unsubstituted or substituted C1-C6-alkyl radical and
- R2 is hydrogen or an unsubstituted or substituted C1-C6-alkyl radical,
- which comprises
- converting continuously added α-isocyanoalkanote esters of the formula II
- 13
- in the presence of continuously added assistants
- at temperatures above 80° C.
- in a reactor to the 5-alkoxy-substituted oxazoles of the formula I
- and continuously removing the reaction products from the reactor.
8 more elements
A process for preparing pyridoxine derivatives of the formula IX
- 14
- where
- R2 is hydrogen or an unsubstituted or substituted C1-C6-alkyl radical,
- which comprises converting amino acids of the formula III
- 15
- to amino esters of the formula IV,
- 16
- where
- R1 is an unsubstituted or substituted C1-C6-alkyl radical,
- converting the latter into formamido esters of the formula V,
- 17
- converting the latter into α-isocyanoalkanoate esters of the formula II,
- 18
- converting the latter in a continuous process step
- in the presence of assistants
- at temperatures above 80° C.
- to 5-alkoxy-substituted oxazoles of the formula I
- 19
- reacting the latter with protected diols of the formula VI VI
- 20
- where
- R3 and R4 independently or R3 and R4 together are a protecting group of the hydroxy function,
- to give the Diels-Alder adducts of the formula VII,
- 21
- and converting the latter by acid treatment and detachment of the protecting group to the pyridoxine derivatives of the formula IX.
22 more elements
Dependencies are inferred from the claim text.