2.6- Diamino-4-phenyl-3,5-pyridine

Murray et al. prepared 2,6-diamino-4-phenyl-3,5-pyridine dicaboxal-dehyde 454 as outlined in Scheme 100. Thus, triethylorthobenzoate 452 is heated with two equivalents of malononitrile in pyridine, followed by aqueous hydrochloric acid, to afford 453 in 43% yields (95T635). A similar... 

Reaction of 4-chloro-6-fluoropyrido[3,4- pyrimidine 59 with [3-methyl-4-(pyridin-3-yloxy)phenyl]amine 60, followed by coupling the formed amine 61 with (3-azabicyclo[3.1.0]hex-6-yl)carbamic acid fi r7-butyl ester, afforded the substituted derivative 62 <2002EPP1249451>. Compound 59 was also reacted with 3-bromoaniline to give the 4-anilino derivative 63 that upon treatment with either methyl- or dimethylamine gave the corresponding 4,6-diamino derivatives 64 (Scheme 2) <1997W09726259, 1995W09519774>. 

Aus 3-Amino-2-benzoyl-4,4,4-trichlor-2-butensaure-nitril und 1,2-Diamino-benzol in Pyridin wird 2-(l-Cyan-2-oxo-2-phenyl-ethyl)-benzimidazol (75% Schmp. 185°) erhalten152. 

Amongst oxidizing reagents, arylsulfonyl chlorides in pyridine simultaneously cyclize and acylate amidinothiourea (and its 2V-phenyl and AT -diphenylhomologs), producing moderate yields of sulfonyl derivatives of 3,5-diamino-l,2,4-thiadiazoles in one step.116... 

Tschitschibabin reaction,290 thus counteracting the example based on 3-hydroxypyridine. The second reaction to be discussed is that of 2-picoline with sodamide at a relatively high temperature, when 3,6-diamino-2-picoline (126) is one of the products isolated.293 If this is so, this represents another example of the type of orientation recently observed in the phenylation of pyridine with phenylcalcium iodide which gave some 2,5-diphenylpyridine.264 Alternatively, a 3,4-pyridyne intermediate (125) might perhaps actually be involved here. The evolution of hydrogen is not mentioned in this case. The decarboxylation of pyridine carboxylic acids under strongly basic conditions is unexceptional. 

Reactions of 1,2,4-thiadiazoles with radicals and electron deficient species are virtually unknown. Catalytic and dissolving metal reductions usually result in S—N bond cleavage. For example, the 5-anilino-3-hydroxy derivative (51) gives a good yield of l-phenyl-2-thiobiuret (52) on Zn-HCl reduction (Scheme 27). Reduction of the diamino derivative (53) gives amidinothiourea (54) from which it may be prepared by oxidation (Scheme 28). Under similar conditions, cleavage of the 3,5-diphenyl derivative (55) results in loss of sulfur and formation of benzylbenzamidine (56 Scheme 29). Reduction of 5-alkylamino-or 5-arylamino-3-alkylthio derivatives (57) with H2S in pyridine-triethylamine or sodium in liquid ammonia yields 1-substituted dithiobiurets (58 Scheme 30). 

Pyrido[2.3-d]pyridin 3-Cyan-4,5-diamino-2-hydroxy-8-phenyl-E9c, 19 [2-(CO —CHj)—3-CN — subst.-py + N2H4]... 

The 1,2-diamino-3-phenylcyclopropenylium ions 3 were also converted into 2-amino-3-phenyl-cyclopropenethiones 4 when treated with hydrogen sulfide and triethylamine or pyridine (see also Section 5.A.2.1.3.). ... 

For the preparation of the 2-amino-4(3i7)-oxo analogues of this series, the 2,4-diamino-9,10-dehydro derivative (IV.175) was converted to (IV.187) (88%, yield) by heating in 1 M NaOH under reflux for 3 h [140a]. Treatment of (IV.187) with acetic anhydride containing a catalytic amount of 4- NJ -dimethylamino)pyridine afforded the 2-acetamido-4-oxo mixed anhydride (IV. 188) (84%), which on careful alkaline hydrolysis was converted to the protected acid (IV. 189) (77%,). Coupling to diethyl L-glutamate in V-methyl-pyrrolidin-2-one in the presence of phenyl iV-phenylphosphoramidochloridate... 

To k] Ionization constants have been reported for a number of amino-, diamino- and hydroxy-pyridines, and nitro- and halogeno-derivatives of these 233 Ionization constant measurements show that, in aqueous solution, phenyl 2-, 3- and 4-picolyl sulphones exist predominantly as such Kt = 107 6 109 6 in their favour). 3- and 4-Phenacylpyridine are chiefly ketonic, but 2-phenacylpyridine contains appreciable amounts of the chelated enol in non-polar media and in the solid state 234a ... 

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