5-Deazaflavins synthesis

Deazaflavin, 5-amino-synthesis, 3, 222 5-Deazaflavin, tetrahydro-oxidative substitutions, 3, 205 Deazaflavinium salts synthesis, 3, 228 5-Deazaflavinoids, 3-aryl-synthesis, 3, 219 Deazaflavins... 

Selected entries from Methods in Enzymology [vol, page(s)] Determination of FMN and FAD by fluorescence titration with apoflavodoxin, 66, 217 purification of flavin-adenine dinucleotide and coenzyme A on p-acetoxymercurianiline-agarose, 66, 221 a convenient biosynthetic method for the preparation of radioactive flavin nucleotides using Clostridium kluyveri, 66, 227 isolation, chemical synthesis, and properties of roseoflavin, 66, 235 isolation, synthesis, and properties of 8-hydroxyflavins, 66, 241 structure, properties and determination of covalently bound flavins, 66, 253 a two-step chemical synthesis of lumiflavin, 66, 265 syntheses of 5-deazaflavins, 66, 267 preparation, characterization, and coenzymic properties of 5-carba-5-deaza and 1-... 

The enzyme complex that catalyses steps d to/of Fig. 25-20 has an unusual composition. An a3 trimer of 23.5-kDa subunits is contained within an icosahe-dral shell of 60 16-kDa (3 subunits, similar to the protein coats of the icosahedral viruses (Chapter 7). The (3 subunits catalyze the formation of dimethylribityllu-mazine (steps d, e), while the a3 trimer catalyzes the dismutation reaction of step/, the final step in riboflavin formation.365 A separate bifunctional bacterial ATP-dependent synthetase phosphorylates riboflavin and adds the adenylyl group to form FAD.366 Two separate mammalian enzymes are required.367 Synthesis of deazaflavins of methanogens (Fig. 15-22) follows pathways similar to those of riboflavin. However, the phenolic ring of the deazaflavin originates from the shikimate pathway.368... 

Subsequent to the synthesis of 5-carba-5-deaza- and 1-carba-1-deazariboflavin, the Merck group synthesized 1,5-dideazari-boflavin, XIV, with both redox-active nitrogens replaced by carbon (22). Some expected patterns of reactivity are observed. The reduction potential for two-electron reduction to the dihydro form, XV, has been estimated at —370 mV, an essentially additive effect from the two deazaflavins previously noted. This low value puts XIV out of the... 

S-Deazaflavins. A new synthesis of 5-deazaflavins (2), in which N5 of a flavin is replaced by CH, involves oxidative cyclization of 5-benzylidene-6-(N-substituted amino)uracils (1) with DAD at 150°. 

Deazaflavines and pyrido[2,3-d 6,5-d ]dipyrimidines, which possess an ability to oxidize an alcohol, are obtained from 6-chloro-5-formyl-3-methyluracil and anilines or 6-aminopyrimidines [76CC203 78CPB3208 81JA5943 84TL(25) 1741 86JHC241]. This method is applied to the total synthesis of coenzyme factor 420 [90JCS(P1)253] (Scheme 100). 

Benzothiopyrano[2,3-c/]pyrimidines(5-deaza-10-thiaflavines) are of special biological interest because of their isosteric and isoelectronic structure to 5-desazaflavine. The synthesis starts from 6-chloro-5-formyl-3-meth-yluracil and thiophenol and subsequent cyclization of the phenylthio intermediate with PPA. Base-catalyzed reduction with secondary alcohols leads to a 5//-benzothiopyrano[2,3-fi(]pyrimidine (78TL2803 81JHC1329). 8-Substituted 5-deazaflavins have been made by a simple approach (cf. (85JHC841) (Scheme 101). 

Dimethoxybenzaldehyde has been employed in the synthesis of deazaflavins (pyrimidoquinolines). Thus, 6-butylamino-3-methyluracil with the aldehyde in dimethylformamide suspension after being heated for 4 hours afforded in 70% yield, 10-butyl-9-methoxy-3-methyl-5-deazaflavin (ref.90). 

A general method for the synthesis of 5-deazaflavins involves the condensation of 6-substituted-aminouracils with o-halogeno-benzaldehydes in dimethylformamide for example,the reaction of (306) with o-bromobenzaldehyde gives (307) in 82% yield. 

The 10-aryl 5-deazaflavin (308) acts as an autorecycling system for the synthesis of -aminoacids by the reductive amination of a-ketoaeids (Scheme 74). 52... 

The reaction of the anilino-uracil (353) with benzaldehyde gives the 5-deazaflavin (354) in excellent yield (Scheme 136)."" An alternative method of synthesis of 5-deazaflavins is illustrated by the conversion of 6-aminouracil (355) into (356) (Scheme 137)."" 5-Deazaflavins act as hydrogen acceptors by addition to positions 1 and 5, and the 1,5-dihydro-compounds that are so formed are readily re-oxidized in air. They have been shown to oxidize benzylamine to benzaldehyde."""... 

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