Isoalloxazine, 7,8,10-Trimethyl

Isay reaction, 2, 79-80 3, 259 Ismelin 7, 656 Isoalloxazine oxidation states, 1, 252 Isoaminopterin synthesis, 3, 327 Isoarsindolines, 1, 543-544 Isoarsinoline, tetrahydro-synthesis, 1, 552-553 stability, 1, 552 Isoascorbic acid structure, 4, 552 ( )-IsoavenacioIide synthesis, 1, 416 Isoazapenem synthesis, 1, 465 Isobacteriochlorin synthesis, 4, 419 Isobacteriochlorin, dimethyl-biosynthesis, 1, 105 Isobacteriochlorin, methyl-biosynthesis, 1, 105 Isobacteriochlorin, trimethyl-biosynthesis, 1, 105 Isobarbituric acid Mannich reaction, 3, 71 synthesis, 3, 133... 

In the s3mthesis of riboflavin and some related flavins, better yields are often available through the use of 5-chloro- or 5,5-dichlorobarbituric acid place of alloxan. In addition to riboflavin, 6-methyl-9-2 i, y-methyl-g- s, 6-ethyl-9-3 , 7-ethyl-9-2 , 6,7-diethyl-9- , 6-ethyl-7-methyl-9-2 .3 , 5,7-di-niethyl-9- , 6,8-dimethyl-9- , 6,7-dichloro-9-29.72 6-chloro-9-3 -, 6-flu-oro-9-3 , 6,7-dibromo-9- , 5,6-dimethyl-9- , 6-chloro-7-methyl-9-2 , 6-meth-yl-7-chloro-9-, 3,6,7-trimethyl-9-(i -D-ribityl)isoalloxazine2 (using 2-methylalloxan), and 6,7-dichloro-9-(i -D-sorbityl)isoalloxazine i have been prepared by this method. 

The availability of the exceptionally successful method for the purification of flavins developed by Pasternack and Brown makes this method the one of choice for the synthesis of several flavins. In addition to riboflavin, [2- C]riboflavin 2 6,7-dimethyl-9-(i -L-lyxityl)isoalloxazine , b-ethyl-y-methyl-9-, 6-methyl-7-ethyl-9-, 6,7-diethyl-9-, and 3,6,7-trimethyl-9-(i -D-ribityl)isoalloxazine ° (using 2-methylbarbituric acid) have been prepared by this method. AT-(i -D-Ribityl)-2-/)-tolylazo-4-ethylaniline , -2-/)-nitrophenylazo-4-chloro-5-methylaniline2 and -2-/>-nitrophenylazo-4-methyl-5-chloroaniline react poorly or not at all with barbituric acid under a variety of conditions. 

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See also in sourсe #XX -- [ ]

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