2.3.5.6- Tetrahydro-imidazo imidazoles

With ketones. The 17/-imidazole-2(377)-thione 378 and 2-mercaptobenzoimidazole 380 reacted separately with cycloheptanone to form the tetrahydro-imidazo[2,l- ]thiazole 379 and the dihydro-thiazolo[3,2-tf]benzimidazole 381, respectively (Equations 170 and 171) <2000JHC943, 2001RJ0564>. 

Glycoluril or Glyoxaldiureide, called in CA Tetrahydro-imidazo[4, d] imidazole-2,5(lH,3H)-dione. See ACETYLENEDIUREIN AND DERIVATIVES in Vol 1, p A65... 

The 2,3,5,6-tetrahydro-imidazo[l,2- ]imidazole system 40, a bicyclic guanidine, has been prepared by treatment of the 2-(2-hydroxyethylimino)imidazolidine 39 with 2-chloro-l,3-dimethylimidazolium chloride (CDIC) (Scheme 27) C2000JOC7779, CHEC-III(11.04.9.1.4)159>. 

Intramolecular cyclization of the imidazoles (433) also gave rise to 4,5,6,7-tetrahydro-imidazo[4,5-c]pyridines (434) (75JHC1039). 

The reaction of l-arylamino-4,4-dimethyl-5-methylene-2,3,4,5-tetrahydro-l//-imidazol-2-one (338 Y = O) and -2-thione (338 Y = S) with protic heterocumulenes affords 7,7,7a-trimethyl-3-aryl-2,3,5,6,7,7a-hexahydro-l/7-imidazo[l,5-fe][l,2,4]triazol-2,5-diones (339 X = Y = 0), and N-and 5-derivatives of these functions in 2- and 5-positions (Equation (104)) <93TH 805-oi, 95FES379>. 

Tetrakis (hydroxymethyl) phosphonium sulfate-urea condensation prod. Tetrakis (hydroxymethyl) phosphonium sulfate (2 1), urea polymer. See Tetrakishydroxymethyl phosphonium sulfate-urea condensate 1,3,4,6-Tetrakis hydroxymethyl tetrahydro imidazo (4,5-D) imidazole-2,5-dione. See Tetramethylolacetylene diurea N,N,N, N -Tetrakis (2-hydroxypropyl) ethylenediamine. See Tetrahydroxypropyl ethylenediamine... 

Imida2o[4,3-d]imidazole, tetrahydro-synthesis, 6, 993 Imidazo[l, 2-n]imidazoles synthesis, 6, 990, 992... 

Octahydro-2,5-bis(nitroimino)imidazo[4,5-[Pg.512]

The 2,3-dioxo-6-thioxo-2,3,5,6-tetrahydro-l/7-imidazo[l,2-A]pyrazole 393 and 5,6-dioxo-2,3-dihydro-l//-imidazo[l,2- ]-imidazole 395 were synthesized by condensation of the respective 5-amino-3-thioxo-2,3-dihydro-pyrazole 392 and 2-aminoimidazoline 394 compounds with either oxalyl dichloride or diethyl oxalate in moderate to poor yields (Equations 178 and 179) <1995JPR472, 2002EJM845>. These cyclizations can suffer from various side reactions such as expulsion of CO, polymerization, or formation of open-chain products. To solve these problems, reagents such as oxalic acid bis-imidoyl- and bis-hydrazoylchlorides 397 and 400 as well as 2,3-dichloroquinoxalines 403... 

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]

The nomenclature for fused 5 5 systems is generally related to the two fused component heterocyclic rings as indicated above for imidazo[4,5-rf]imidazole (1), although compounds are sometimes named as hetero derivatives of pentalene. Heterocycles which are not fully conjugated can be named as dihydro, tetrahydro, etc., derivatives of the fully conjugated parent system or as hetero derivatives of the saturated parent hydrocarbon. For example heterocycle (6) can be named as a tetraaza bicyclo[3.3.0]octane. 

The thermally stable l,2-diethylene-3-(3-nitrophenyl)guanidine (291) rearranges to l-(3-nitrophenyl)-2,3,5,6-tetrahydro-l//-imidazo[l,2-a]imidazole (292) when treated with Nal in refluxing acetone. Attempted reduction (LiAfflU) or oxidation (Hg(OAc)2) of the guanidine moiety was unsuccessful (70ZN(B)119l). 

Amino-6-nitro-2,3-dihydro- und entsprechende Pyrimidino[l,2-a]pyrimidine werden durch Hydrazin und substituierte Hydrazine unter Bildung von 4-Ni-tro-5-[(4,5-dihydro-lH-imidazol-2-yl)-amino]-l H-pyrazolen bzw. 4-Nitro-5-[(3,4,5,6-tetrahydro-2-pyrimidinyl)-amino]-l H-pyrazoIen gespalten1258. 

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