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Ethers pyridoxine synthesis

Cycloaddition of nitriles with dipropargyl ethers. A new synthesis of pyridoxine (4, vitamin BJ is based on the (2 + 2 + 2 cyclo.iddition of acetonitrile with dipropargyl ethers catalyzed by Cp,Co or Cp(CO),Co to torn the pyridine derivative I. Subsequent steps involve rearrangement of the N-oxide of 1 to the 3-hydroxypyridine 2 with acetic anhydride. The final step involves the known cleavage of the dihydrofuranc ring. [Pg.180]

CP2C0 catalyses the condensation of acetylene and mono-substituted acetylenes (but not di-substituted acetylenes) with nitriles at 150° to give 30-70% yields of substituted pyridines [WakatsuM Yamazaki Synthesis 26 1976], This synthesis has been applied successfully in a 2+2+2 cycloaddition reaction between di(trimethylsilyl)propargyl ether and acetonitrile to prepare a pyridine intermediate whieh was used to obtain pyridoxine (vitamin Be) [Greiger et al. Helv Chim Acta 67 1274 1984. ... [Pg.673]

Most physiologically active compounds owe their biological properties to the presence of heteroatoms, mainly in the form of heterocydes. A majority of the known natural products are heterocyclic. It is therefore not surprising that more than half the published chemical literature deals with such compounds—then-synthesis, isolation, and interconversions. Indeed, we have already encountered many examples—the cyclic ethers (Section 9-6), acetals (Sections 17-8, 23-4, and 24-8), carboxylic acid derivatives (Chapters 19 and 20), and amines (Chapter 21). The bases in DNA, whose sequence stores hereditary information, are heterocydes (Section 26-9) so are many vitamins, such as Bi (thiamine. Real Life 23-2), B2 (riboflavin. Real Life 25-3), Bg (pyridoxine), the spectacularly complex B12, and vitamins C and E (Section 22-9). The structures of vitamins Bg and B12, as well as additional examples of heterocyclic systems and their varied uses, are depicted here. [Pg.1121]


See other pages where Ethers pyridoxine synthesis is mentioned: [Pg.1214]   
See also in sourсe #XX -- [ Pg.5 ]

See also in sourсe #XX -- [ Pg.5 ]




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