PYRIDOXINE 



Hoftmann-La Roche ^^ also patented the condensation of malono- 

 nitrile, malonic esters, malonic acid diamide or cyanacet amide with 

 2-amino-5-ethoxy-pent-2 : 3 -en -4 -one to give 4 - ethoxymethyl - 6 - 

 hydroxy-2-methyl-pyridines containing a carbethoxy, amido or cyano 

 group in position 5 : 



CHaOEt 

 I 



CH, 



where R = . COOEt, . CONH2 or . CN. 



A further patent ^^ covers the condensation of acylacetones with 

 malononitrile in presence of piperidine, dimethylamine, diethylamine 

 or dipropylaniine : 



R 



do 



R 



CHo . CO 



CH2 -h 

 I 



CH2 . CN 



I 

 CN 



CHc 



CN 



^N^ 



Roche Products Ltd.^^a patented the conversion of 4:5- 

 dicarbalkoxy-3-hydroxy-2-methyl-pyridines (pyracin esters) into pyri- 

 doxine (a) by reacting with a phenylarylmethyldialkylammonium 

 hydroxide to yield 3-arylmethoxy-4 : 5 -dicyano-2-methyl- pyridine, 

 treating with ammonia to give the corresponding diamide, dehydrating 

 and then hydrogenating to 4 : 5-bis-aminomethyl-3-hydroxy-2-methyl- 

 pyridine ; or (b) by reducing with lithium aluminium hydride. 



Another method of synthesising pyridoxine was patented by 

 Lederle Inc.^^ 



COOEt 



H 



NHo 



CONH2 



CN 



CHaVXo 

 H 



CN 



CN 



H 



CN 



HNO3 O.^ 

 ' CH ' 



/ 



3\ / 



^N 

 H 



CN 

 O 



PCI5 



0,N(j^' 



CN 

 CN 



CH3. 



'^N^ 



H2 



CH2NH2 CH 



H^N^VHaNH, HNO. H0/\ 



CI 



CH, 



V 



CH20H 



CHj 



V 



306 



