3.4- Dioxo phthalazines

Dioxo-2,3-dimethyl-1,2,3,4-tetrahydro-phthalazin wird in Acetat-Puffer im we-sentlichen zuml-Oxo-2,3-dimethyl-l,2,3,4-tetrahydro-phthalazin (80% d.Th.) reduziert, in 4n Salzsaure wird dagegen unter Methylamin-Abspaltung 1 -Oxo-2-methyl-2,3-dihy-dro-isoindol (46% d.Th.) erhalten1 (vgl. a. S. 595f.) ... 

The silylation-amination of 5,10-dihydroxy-l,4-dioxo-l,2,3,4-tetrahydroben-zo[g]phthalazine 281 for 27 h at 170 °C with excess N(2-aminoethyl)piperidine 282 and HMDS 2 proceeds with catalytic amounts of Ts0H-H20 to afford, via the activated persilylated intermediate in which the sensitive phenolic hydroxy groups are protected, the 1,4-bis-amine 283 in 67% yield. All conventional efforts with POCI3, PCI5, or SOCI2 to convert 281 into the corresponding 1,4-dichloro compound, to be followed by amination, resulted in failure [86] (Scheme 4.35). 

Diacylbenzenes with hydrazine form phthalazines 409. Monoxo compounds of type 410 result from 0-acylbenzoic acids and hydrazine or hydroxylamine, and dioxo derivatives 411 from phthalic acid derivatives with N2H4, NH2OH, or H202. Phthalodinitrile is converted by methanolic hydrazine into 1,4-diaminophthalazine 412 <1968JHC111>. 

Phthalazine l,4-Dihydroxy-6-methyl- E9a, 752 (subst. Phthalanhydrid/N2H4) Pyrazolidin 3,5-Dioxo-l-phenyl-VII/4, 301... 

Dioxo-1,2,3,4-tetrahydrophtha lazin-5-earbonyl Azide [called 1.4-Dioxo-1.2.3.4-tettahydto-phthalazin-carbonsaute-(5) Azid in Get],... 

Dicyano(phthalazm-l-io)methanide (166) with acetylethylene gave a separable mixture of 1-emfo-acetyl- and l-ev >-acetyl-l, 340b-tetrahydropyrrolo[2,l-a] phthalazine-2,3-dicarbonitrile (167) (MeCN, 20 C, 4h 72% and 23%, respectively), with stilbene gave l,2-diphenylpyrrolo[2,l-a]phthalazine-3-carbonitrile (168) (MeCN, reflux, 24 h 60%), or with 7V-p-methoxyphenylmale-imide gave 9,1 l-dioxo-8a,9,10,l 1,1 la,llb-hexahydro-8/7-pyrrolo[3, 4 3,4]pyr-rolo[2, l-a]phthalazme-8,8-dicarbonitrile (169) (MeCN, 20°C, 24 h 91%)P ... 

Ethoxycarbonyl-5,7-dimethyl-8-nitro-4-oxo-3,4-dihydro-1-phthalazinec ar-boxylic acid (92) underwent reduction to its 8-amino analog followed by spontaneous cyclization to afford ethyl 4,6-dimethyl-3,8-dioxo-2,3,7,8-tetra-hydropyrrolo[4,3,2-tie]phthalazine-5-carboxylate (93) (H2, Pd/C, EtOH,... 

Multicomponent approaches toward the formation of more complex phthalazine-containing compounds were reported in 2014. A four-component one-pot condensation reaction was employed by Dabiri and coworkers to generate (1,2,3-triazol-4-yl)methyl-3-amino-5,10-dihydro-5,10-dioxo-lH-pyrazolo[l,2-f)]phthalazine-2-carboxylates 26 (Scheme 18) (14SC2037). Catalyzed by Cu(OAc)2 (10mol%) and sodium ascorbate (20mol%), the reaction of benzaldehyde derivatives (1 equivalent), azides (1 equivalent), prop-2-ynyl-2-cyanoacetate (27) (1 equivalent), and phthalhydrazide (28) (1... 

Dioxo.3.ellyl-2-plienyl-tetiahydn>> phthalazin 84II190. 

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