4- Methoxy-6-phenyl-1,2,4-triazine, reaction with

J(P1)2549, 2004S2893>, as exemplified by the reaction of 3-methylthio-5-methoxy-l,2,4-triazine 85 with phenyllithium leading to 3-methylthio-5-methoxy-6-phenyl-l,2,4-triazine 86 (Scheme 48) <2002J(P1)2549>. 

Upon activation by boron trifluoride, 5-methoxy-3-phenyl-l,2,4-triazine reacts with resorcinol at room temperature in the presence of air to give the corresponding benzofurotriazine 163 due to the tandem Sn and reactions... 

The chemistry of l-methyl-truns-cyclo-octene has been studied. In particular it reacts with acidic methanol to give 1-methoxy-l-methylcyclo-octane, with bromine to give a complex mixture, and with peracid to give its epoxide. On warming in acetic acid it is isomerized to 1-methyl-cis-cyclo-octene, and it reacts with diazomethane and phenyl azide to give cycloaddition products. With 4-phenyl-1,2,4-triazine-3,5-dione, the ene product (121) is obtained. The major difference in reactivity between trans-cyclo-octene and its 1-methyl analogue was found for electrophilic addition reactions where the stability of the incipient 3° cation made the 1-methyl compound more reactive.Transannular products were obtained from the reaction between trans-... 

The methoxy group is replaced in the reaction of 3-methoxy-5-phenyl-1,2,4-triazine 1-oxide 46 with ammonia, resulting in 3-amino-5-phenyl-1,2,4-triazine 1-oxide 47. The treatment of 3-methoxy-1,2,4-triazine 1-oxide 20 with hydrazine leads to 3-hydrazino-1,2,4-triazine 1-oxide 48 (71JOC787). 

The reaction of 3-methoxy-1,2,4-triazine 1-oxide 20 with the carbanion generated from chloromethyl phenyl sulfone proceeds as the vicarious nucleophilic substitution (VNS) of hydrogen (Scheme 1, path B) via addition of the carbanion at position 5 of the heterocycle. Following base-induced elimination of HCl and protonation, 3-methoxy-5-phenylsulfonyl-1,2,4-triazine 4-oxides 65 result (88LA627). 

One route to these compounds is the reaction of 3-amino-1,2,4-triazoles (312) with dicyanodiamide (485) to yield (49USP2473797 53JOC1610) 5,1-diamino-l,2,4-triazolo[4,3-a]l,3,5-triazines (486). The 1,3,5-triazine ring of 7-methoxy-3-phenyl-l,2,4-triazolo[4,3-a] 1,3,5-triazine (489) was formed (70T3357) by the direct cyclocondensation of 0-methyl-N-(5-phenyl-l,2,4-triazol-3-yl)urea (488) with methyl diethoxyacetate (487) or triethyl orthoformate. 3,5,7-Triamino-1,2,4-triazolo[4,3-a] 1,3,5-triazine (490) was prepared (53JOC1610 63ZOB1355) in one step by the reaction of two equivalents of dicyanodiamide (485) with one equivalent of hydrazine dihydrochloride. 

Nucleophilic substitution of hydrogen Sn can also be combined with the displacement of a good leaving group as illustrated by the reaction of 3-phenyl-5-methoxy-l,2,4-triazine with resorcinol, proceeding via the intermediate o -adduct and affording benzofuro[2,3-e]-l,2,4-triazine according to the tandem Sn -Sn cyclization protocol (Scheme 57) [175]. 

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