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Kobalt‐katalysiert Cycloadditionen von Alkinen und Nitrilen zu Pyridinen: Ein neuer Zugang zu Pyridoxin (Vitamin B 6 )
Author(s) -
Geiger Rudolf E.,
Lalonde Michel,
Stoller Hansijörg,
Schleich Kuno
Publication year - 1984
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19840670513
Subject(s) - chemistry , pyridoxine hydrochloride , cycloaddition , pyridoxine , medicinal chemistry , curtius rearrangement , pyridine , hydrolysis , catalysis , stereochemistry , organic chemistry , biochemistry
Cobalt‐Catalyzed Cycloaddition of Alkynes and Nitriles to Pyridines: A New Route to Pyridoxine (Vitamin B 6 ) A new synthesis of pyridoxine hydrochloride ( 1 ) based on a Co‐catalyzed cycloaddition of MeCN with substituted di(2‐propynyl) ethers ( 3 and 16 ) is described. The reaction sequences following cycloaddition and leading to 1 involve as key steps the rearrangement f the pyridine‐ N ‐oxide 6 to the 3‐hydroxypyridine 7 with Ac 2 O and a modified Curtius rearrangement of the acid 19 and subsequent diazotation and hydrolysis to the same pyridoxine precursor 7 , respectively. The intermediate 7 is transformed to 1 by well‐known procedures.