- Preparation method of high content vitamin B6
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The invention relates to a preparation method of a high content vitamin B6. According to the method, 1,5-dihydro-3,3-disubstituent group-8-methyl-9-alkyl carbonyl oxypyrido [3,4-e]-1,3-dioxane is prepared by the Diels-Alder addition reaction, aromatization reaction and esterification reaction of 4-methyl-5-alkoxyl-oxazole and 2,2-disubstituent group-4,7-dihydro-1,3-dioxepine in the presence of ananhydride through the "one-pot method", and then vitamin B6 is prepared by deprotection. According to the method, the stability of the raw materials of 4-methyl-5-alkoxyl-oxazole and 2,2-disubstituentgroup-4,7-dihydro-1,3-dioxepine are ensured, the reaction is thorough, and the selectivity is high, so that the method provides guarantees for the preparation of high content medicinal vitamin B6.
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Paragraph 0039-0042
(2019/07/16)
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- MANUFACTURE OF VITAMIN B6
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A process for manufacturing a 3-unsubstituted, 3-monosubstituted or 3,3-disubstituted 9-acyloxy-1,5-dihydro-8--methylpyrido[3,4-e] [1,3]dioxepin (I) and optionally for manufacturing pyridoxine involves performing an addition reaction between a 4-methyl-5-alkoxy-oxazole (II) and a 2-unsubstituted, 2-monosubstituted or 2,2-disubstituted 4,7-dihydro-(1,3)-dioxepin (III) in the substantial absence of a solvent and a catalyst to give a product mixture consisting essentially of the appropriate Diels-Alder adduct (IV) in a major proportion and the appropriate 3--unsubstituted, 3-monosubstituted or 3,3-disubstituted 1,5-dihydro-8-methylpyrido[3,4-e] [1,3]dioxepin 9-ol (V) in a minor proportion, removal of a substantial proportion of the unreacted oxazole and dioxapin starting materials from the product mixture by distillation under reduced pressure, addition of a substantially anhydrous organic acid to said product mixture and rearrangement of the Diels-Alder adduct IV to further V in the presence of said substantially anhydrous organic acid with removal of the generated alkanol by distillation under reduced pressure, and acylation of the resultingly enriched quantity of V with an added carboxylic acid anhydride to produce the desired I, and optionally converting this so-manufactured acylation product I to pyridoxine by acid hydrolysis for achieving deprotection and deacylatiom. Pyridoxine is a well known form of vitamin B6 with well established utility.
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Page/Page column 15
(2008/06/13)
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