Pyridazine 3-phenyl-5-nitro

The synthesis of pyrrolo[2,3- 7 pyridazines can be achieved by starting either with pyridazine, a tetrazine, or a pyrrole. Pyridazinone 80 reacts with bromomethyl derivatives to give poor yields of 81 <1996H(43)1863> (Equation 34), while 5-acetyl-2-methyl-4-nitro-6-phenyl-3(2//)-pyridazinone, after treatment with sarcosine ethyl ester for a brief time at room temperature, followed by acid hydrolysis afforded a good yield of 82 (70%) <1994S669>. 

Pyridazine 4-Amino-5-nitro-3-phenyl- E9a, 617 (H -> NH2) Pyrido[2,3-d pyrimidin 6-Cyan-4-hydroxy-7-methoxy-2-methyl-E9c, 93 [2-NH2 —3-(CO—... 

Amino-6-hydroxy-4-hydroxy-methyl-3-phenyl- E9a, 589 (7-OH — 4-Ar — < 1,2-oxazolo-[3,4-d]pyridazine)/Red.) Pyrido[l,2-a]benzimidazol 7-Nitro-... 

Pyridazin 6-Hydroxy-l-methoxycar-bonyl-3-(4-nitro-phenyl)-l, 4,5,6-tetrahydro- E14a/2. 350 (Imin +, .En-on )... 

Nitration of tetrazolo[l,5-a]quinoxaline (10) and its 4-oxo derivative (29) was investigated and was found to lead to two different selective substitutions the fully aromatic compound (10) gave 7-nitro derivative (28) (Equation (5)), whereas the lactam (29) afforded 8-nitro product (30) (Equation (6)) <92JMC3319>. Reactivity of phenyltetrazolo[l,5-Z>]pyridazines was also described <75MIP59122> and nitration of the substituent phenyl ring was reported. 

Ethyl 5-amino-4-oxo-3-p-tolyl-3,4-dihydrothieno [3,4-d] pyridazin-l-carboxylate (295) and p-dimethylaminopropiophenone (presumably converted by loss of dimethylamine into phenyl vinyl ketone under the reaction conditions) probably gave the intermediate adduct (296) that lost H2S to afford ethyl 5-amino-7-benzoyl-4-oxo-3-p-tolyl-3,4-dihydro-1 -phthalazinecarboxylate (298) (Mc2NCHO, trace AcOH, reflux, 2h 61%) the same substrate (295) with p-methoxy-p-nitrostyrene likewise gave ethyl 5-amino-7-p-methoxyphenyl-6-nitro-4-oxo-3-p-tolyl-3,4-dihydro-l-phthalazinecarboxylate (297) (80%) and many analogs were made similarly. ... 

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