Imidazole tetrahydro

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

Dihydro-l//-imidazol-2-yl) derivatives were prepared from ethyl 2,3,6,7-tetrahydro-5//-pyrido[l,2,3-e/e]-l,4-benzoxazine-2-carboxylates and ethyl 5-oxo-2,3-dihydro-5//-pyrido[l,2,3-e/e]-l,4-benzoxazine-2-carboxy-lates with 2M Me3Al in toluene and H2NCH2CH2NH2 at reflux temperature for 3 h (99EUP894796). 

Chemical Name 4,5-Dihydro-2-(1,2,3,4-tetrahydro-1-naphthalenyl)-1 H-imidazole hydrochloride... 

Addition to Tetrahydro-2//-l,3-oxazines, Hexahvdro-1 f/-pyrrolo[l,2-r]imidazoles and... 

Dioxo-l,3-dimethyl-tetrahydro-imidazol- (4-spiro-2) - 4,6,7-trimethyl-1,2,3.4-tetrahydro-chinoxalin ... 

Die Reduktion kann bis zum 3-Oxo(Thiono)-5,6-diphenyl-hexahydro-l,2,4-triazin weitergeftihrt werden, dabei wird jedoch beim 3-Oxo-tetrahydro-Derivat in Acetonitril bei pH — 1 (-1,0 V) unter Ringverengung das 2-Hydroxy-4,5-diphenyl-imidazol (50% d.Th. F 318°) gebildet. Zur Reduktion der N-Alkyl-l,2,4-triazinone s, S. 613. 

H-Purin und 6-Amino-purin (unter Ammoniak-Abspaltung) liefern in waBrigen Puf-ferlosungen an Quecksilber l,2,3,6-Tetrahydro-9H-purin, das zu 5-Amino-4-(hydroxy-methylamino-methyl)-imidazol hydrolysiert werden kann2. 

CN 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl- 1/7-imidazol-1 -yl)methyl]-4H-carbazol-4-one... 

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

The hydroxyl group was usually protected, because cyanohydrins have tendency to racemization or even decomposition. Vinyl ethers or acetal and acid catalysts furnish acetals [62]. Trialkylsilyl chlorides and imidazole are used to give silyl ethers [63]. Commonly used protective groups are silyl ether, ester, methoxy isopropyl (MIP) ether, and tetrahydro-pyranyl ether. ( -Protected cyanohydrins are tolerant to a wider range of cyanide/nitrile transformations and are utilized widely in the synthesis of compounds of synthetic relevance in organic chemistry. 

In his approach toward selenium-containing heterocycles with potential biological activity, Abdel-Hafez reacted 2-amino-3-(4,5-dihydro-17/-imidazol-2-yl)-4,5,6,7-tetrahydro-l-benzoselenophene 297 with triethyl orthoformate and benzaldehyde to generate the tricyclic systems 296 and 298, respectively (Scheme 21) <2005RJ0396>. Similarly, reaction with carbon disulfide gave the corresponding thiourea 299. 

Several pyrrolo[l,2-f] imidazoles have been studied for their physiological activities. Most of these compounds demonstrated a high affinity for the 5-HT1A receptor. Pyrrolo[l,2-o]imidazoles are present in the literature as tetrahydro, perhydro, 1-oxoperhydro, 3-oxoperhydro, 7-oxoperhydro, 1,3-dioxoperhydro, 1,5-dioxoperhydro, 2,7-dioxoperhydro, and 1 -thio-3-oxoperhydro derivatives. 

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>. 

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... 

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