1.2.4.10- Tetrahydro-3//-pyrazolo

The Ulmann reaction of 4-bromo-3-(2-aminophenyl)thiomethyl-3-pyra-zolin-5-ones (74) in a nonpolar solvent such as xylene and in the presence of a small amount of pyridine afforded 1,2,4,10-tetrahydro-3//-pyrazolo[3,4-c][l,5]benzothiazepin-3-ones (75). However, when the same reaction was... 

Pyrazolone-1,2-dioxides 311 were subjected to cycloaddition with a wide range of olefinic compounds leading to the 0-2,3,3 ,4-tetrahydro-pyrazolo[l,5-3]isoxazole cycloadducts 312. The behavior of these reactive species 311 toward unsaturated compounds, stereochemical and mechanistic aspects, were discussed in details (Equation 134) <1994J(P2)1337>. 

Dioxo-l, 23,6-tetrahydro- [pyrazolo-3, 44,5-pyridazin] -5-carbonyl azide 5 D1406... 

Organ and co-workers [120] described a unique approach to MCRs using a microwave-assisted, continuous flow process for the synthesis of new series of tetrahydro-pyrazolo[3,4-6]quinolin-5(6//)-ones 79. An aldehyde, dimedone, and 5-amino-3-methyl-l//-pyrazole were reacted, yielding the desired compound 79 in moderate to excellent yields. It was proved that the electronic properties of the substituted benzaldehydes have an important impact on the conversions as with electron-donating groups rather low yields were obtained (Scheme 60). 

A microwave-assisted three-component coupling reaction of 5-amino-3-phenyl-pyrazole, a cychc 1,3-dicarbonyl compound and an aromatic aldehyde has been described by Chebanov and co-workers [121]. Depending on the apphed reaction conditions a series of 4-aryl-3-phenyl-l,4,6,7,8,9-hexahydro-l// pyrazolo[3,4-h] quinolin-5-ones 80, 9-p-tolyl-6,6-dimethyl-2-phenyl 5,6,7,9-tetrahydro-pyrazolo [5,l-h]quinazolin-8-ones 81, or 4-aryl-5a-hydroxy-4,5,5a,6,7,8-hexahydropyra-zolo[4,3-c]quinolizin-9-ones 82 can be formed (Scheme 61). 

Die analogen 3(5)-Anilino-Verbindungen cyclisieren dagcgcn zu l,2,3,4-Tetrahydro-2404. 

Anilino-5(3)-aryl-lH-pyrazole kondensieren mit Formaldehyd und primaren Aminen zu 2-Aryl-4-phenyl-4,5,6,7-tetrahydro-[Pg.693]

Eine weitcre Uberbriickungzwischen Heterocyclus und Carbocyclus gelingt bci der Reaktion von 7-Amino-IH-indazol mit 2,4-Pentandion mit anschlieBender reduktiver Cyclisierung. Dabei wird die Bildung dia-stereomerer 4,6-Dimethyl-4,5,6,7-tetrahydro-[Pg.850]

Almost simultaneously Cederbaum (Ciba-Geigy) [60] as well as Fischer and coworkers [61] claimed the herbicidal activity of 2-mesityl-tetrahydro-pyrazolo-1,3-diones 4. 

Pyrazolo[3,4-c]pyrazole, tetrahydro-rearrangement, 5, 250 Pyrazolo[4,3-c]pyrazole, tetraaryl-electrophilic substitution, 6, 1035 oxidation, 6, 1034-1035 reduction, 6, 1035 vacuum pyrolysis, 6, 1035 Pyrazolo[ 1,2-n]pyrazole-1,5-diones synthesis, 6, 991 Pyrazolo[ 1,2-n]pyrazoles reactions, 6, 1038 ring opening, 6, 983... 

A library of fifteen 6,7,9,9a-tetrahydro-57/-pyrazolo[l,2-tf]pyrrolo[3,4-ir]pyrazole-l,3,5(2/7,3a7/)-triones 712 was prepared by combinatorial stereoselective cycloadditions of compounds 320 to A-substituted maleimides. 

Quiroga J, Mejia D, Insuasty B et al (2001) Regioselective synthesis of 4, 7, 8, 9-tetrahydro-2H-pyrazolo[3, 4-b]-quinolin-5(6H)-ones. Mechanism and structural analysis. Tetrahedron 57(32) 6947-6953... 

Jarro Q, Braulio I, Angelina H et al (1998) Synthesis of 4-aryl-4, 7, 8, 9-tetrahydro-6H-pyrazolo[3, 4-b]quinolin-5-ones. J Heterocycl Chem 35(3) 575-578... 

Reaction of 2-amino-3-phenylazo-5-methyl-6,7-dihydropyrazolo [ 1,5-a] -pyrimidine-7-one (209) with ACOH/H2SO4 gives the pyrazolo[l,5-a]-pyrimidine derivative 210 (77JHC155). This reaction can be looked at as electrophilic substitution of the arylazo function by the proton. Similarly, 4,5,6,7-tetrahydro-2-phenyl-3-phenylazo-5-oxopyrazolo[l,5-a] pyrimidine gives 4,5,6,7-tetrahydro-2-phenyl-5-oxopyrazolo[l,5-a]pyrimidine 212 by the action of acetic/hydrochloric acid (75T63). 

Methyl 7-Methyl-l,3-dioxo-2-phenyl-2,3,6,7 tetrahydro-5,6-methano-l//,5//-pyrazolo l,2- ] l,2,4 triazole-5-carboxylate (310 Typical Procedure, Thermal Synthesis 45... 

The presence or absence of the dioxolane protecting group in dienes dictates whether they participate in normal or inverse-electron-demand Diels-Alder reactions.257 The intramolecular inverse-electron-demand Diels-Alder cycloaddition of 1,2,4-triazines tethered with imidazoles produce tetrahydro-l,5-naphthyridines following the loss of N2 and CH3CN.258 The inverse-electron-demand Diels-Alder reaction of 4,6-dinitrobenzofuroxan (137) with ethyl vinyl ether yields two diastereoisomeric dihydrooxazine /V-oxide adducts (138) and (139) together with a bis(dihydrooxazine A -oxide) product (140) in die presence of excess ethyl vinyl ether (Scheme 52).259 The inverse-electron-demand Diels-Alder reaction of 2,4,6-tris(ethoxycarbonyl)-l,3,5-triazine with 5-aminopyrazoles provides a one-step synthesis of pyrazolo[3,4-djpyrimidines.260 The intermolecular inverse-electron-demand Diels-Alder reactions of trialkyl l,2,4-triazine-4,5,6-tricarboxylates with protected 2-aminoimidazole produced li/-imidazo[4,5-c]pyridines and die rearranged 3//-pyrido[3,2-[Pg.460]

Treatment of the dihydropyrazole (255) with thionyl chloride gives 2,3,6,7-tetrahydro-l//-pyrazolo[l,2-a]pyrazol-4-ium chlorides (256). The imonium group is readily reduced with LiAltU to give (257), whereas base-catalyzed air oxidation at C-3 in (256) followed by loss of H20 or H202 gives (258) (68JOC3941). 

Tetrahydro-lH-pyrazolo[3,4-c]pyridine derivatives, (II), and other 5-6 to 5-7 heterobicycles prepared by Pinto (3) were effective as trypsin-like serine protease inhibitors, especially for factor Xa. 

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