Imidazole 2-propyl

A silica gel containing 3-imidazole propyl groups bonded to surface atoms of silicon has been prepared (253), and was treated 254) with a solution of Fe(TPP)L2, where L = py or pip, where upon the iron(II) porphyrin became attached to the imidazole groups on the surface of the gel,... 

Alkyl radicals produced by oxidative decarboxylation of carboxylic acids are nucleophilic and attack protonated azoles at the most electron-deficient sites. Thus imidazole and 1-alkylimidazoles are alkylated exclusively at the 2-position (80AHC(27)241). Similarly, thiazoles are attacked in acidic media by methyl and propyl radicals to give 2-substituted derivatives in moderate yields, with smaller amounts of 5-substitution. These reactions have been reviewed (74AHC(i6)123) the mechanism involves an intermediate cr-complex. 

Imidazole, 5-hydroxy-1 -isopropyl-2-methyl-4-propyl-synthesis, S, 475 Imidazole, 2-hydroxymethyl-hydroxymethylation, S, 404 oxidation, S, 430 Imidazole, 4-hydroxymethyl-oxidation, S, 430 synthesis, S, 480, 484 Imidazole, 2-hydroxymethyl-4-methyl-synthesis, S, 484... 

Rh(III)(NHC) hydrides have been studied as catalysts for this type of hydrogenation. The products from the reaction of Rh(I) complexes with are dependent on the natnre of the NHC. The reaction of [RhCl(IPr)2(N2)] 1 (IPr = Af,A -bis-[2,6-(di-tTo-propyl)phenyl]imidazol-2-ylidene) with gave the monomeric complex 3 [1], which was also obtained from the reaction of [RhCl(COE)(IPr)]2 2 with and excess IPr, while the reaction of [RhCl(COE)(lMes)]2 with gave the chloride bridged species 4 (Scheme 2.1) [2],... 

However, similar NHC architectures employing aromatic side chains have shown more encouraging results. In 2000, Nolan and co-workers reported the synthesis and characterisation of the NHC-Ru complex 20 bearing a sterically more demanding N,N -bis-[2,6-(di-/xo-propyl)phenyl]imidazol-2-ylidene (IPr) ligand [27, 28] (Fig. 3.5). Standard RCM substrate 1 was used to test the catalytic performance of 20. The ring closure was found to be complete after 15 min by using 5 mol% 20 as catalyst at room temperature. Under identical conditions, 15... 

In 2002, Leadbeater and Torenius reported the base-catalyzed Michael addition of methyl acrylate to imidazole using ionic liquid-doped toluene as a reaction medium (Scheme 6.133 a) [190], A 75% product yield was obtained after 5 min of microwave irradiation at 200 °C employing equimolar amounts of Michael acceptor/donor and triethylamine base. As for the Diels-Alder reaction studied by the same group (see Scheme 6.91), l-(2-propyl)-3-methylimidazolium hexafluorophosphate (pmimPF6) was the ionic liquid utilized (see Table 4.3). Related microwave-promoted Michael additions studied by Jennings and coworkers involving indoles as heterocyclic amines are shown in Schemes 6.133 b [230] and 6.133 c [268], Here, either lithium bis(trimethylsilyl)amide (LiHMDS) or potassium tert-butoxide (KOtBu) was em-... 

H-imidazol-4-yl]propyl 4-[F-18]fluorobenzyl ether ([F-18]fluoroproxyfan) A potential radioligand for imaging histamine H-3 receptors, J. Label. Compds Radiopharm. 43 (2000) 872-893. 

C.J. Koch, S.M. Flahn, K.J. Rockwell, J.M. Covey, W.G. McKenna, S.M. Evans, Pharmacokinetics of EF5 [2-(2-nitro-1-FI-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoro-propyl) acetamide] in human patients Implications for hypoxia measurements in vivo by 2-nitroimidazoles, Cancer Chemother. Pharmacol. 48 (2001) 177-187. 

Die durch Fluorid-Ionen induzierte Cyclisierung von Dichlor-essigsaure-[N-(2-trimethylsilyl-oximino-propyl)-anilid] fiihrt direkt zu 2-Formyl-4-methyl-l-phenyl-imidazol-3-oxidni. Die eigentlich erwartete 2-Dichlormethyl-Verbindung konnte nicht isoliert werden. 

Die basenkatalysierte Umsetzung kann auch in Nitrobenzol mil Pyridin als Katalysator [Her-stellung von mehreren 1-(3-Aryloxy-2-hydroxy-propyl)-2-methyl-4-nitro-imidazo-len 38-58%]87t, ohne Losungsmittel mit Kaliumcarbonat als Katalysator [l-(3-ChIor-2-hydroxy-propyl)-2-methyl-4-nitro-imidazol 60%]872 oder in Ethanol mit Natriumhydroxid als Katalysator [l-(2-Hydroxy-ethyl)-2-methyl-4-nitro-imidazol 100%]873 durchgefuhrt we.r-den. Statt Oxiran kann auch 2-Oxo-l,3-dioxolan eingesetzt werden. Dabei entstehen ohne Katalysator bei 160° die 1,4-Regioisomeren [z. B. 2,5-Dimethyl-l-(2-hydroxy-ethyl)-4-nitro-imidazol 60%]874... 

Neben Oxiranen oder 2-Oxo-l,3-dioxolan werden zur N-Alkylierung von Imidazolen manch-mal auch andere Heterocyclen verwendet, die in der Lage sind, unter Ringoffnung Nukleophile zu addieren. So kann 2-Methyl-4(5)-nitro-imidazol mit l,2-Oxathiolan-2,2,-dioxid (Propansul-ton) zu 2-Methyl-5-nitro-l-(3-sulfo-propyl)-imidazol (48%) und mit 2-Oxo-oxetan zu l-(2-Carboxy-ethyl)-2-methyl-4-nitro-imidazol umgesetzt werden875. 

Zur Herstellung von 2,4-Dibrom-5-methoxycarbony l-l-methyl-imidazol aus 5-Methoxycarbo-nyl-1 -methyl-imidazol wird mit N-Brom-acetamid in Brom-trichlor-methan unter Katalyse von Bis-[l-cyan-2-methyl-propyl]-diazen radikalisch bromiert (81% Ausbeute)660. 2-Benzylthio-4(5)-methyl-imidazol wird in Tetrachlormethan mit Brom und Dibenzoylperoxid als Katalysator ebenfalls radikalisch zu 2-Benzyhhio-4(5)-brom-5(4)-methyl-imidazol umge-setzt657. 

Tab. 7 (S. 153) zeigt einige durch Metallierung in 5-Position mit Butyl-lithium oder 1-Methyl-propyl-lithium hergestellte Imidazole.

Tab. 7 1,2,5-trisubstituierte Imidazole aus 1,2-disubstituierten Imidazolen mit Butyl- bzw. l-Methyl-propyl-lithium und... 

So wird aus 5-Chlor-937, 5-Brom-905 oder 5-Iod-l-methyl-4-nitro-imidazol905 durch Umsetzung mit Kaliumcyanid in Ethanol oder Dimethylformamid in Ausbeuten von 85, 68 bzw. 61% 5-Cyan-l-methyl-4-nitro-imidazol erhalten. Auch 5-Brom-l,2-dimethyl-4-nitro-938, 5-ChIor-l-ethyl-4-nitro-2-propyI-939 und l-Butyl-5-chlor-2-methyl-4-nitro-939 liefern 5-Cyan- 1,2-di-methyl-4-nitro-, 5-Cyan-l-ethyl-4-nitro-2-propyl- (81%) bzw. l-Butyl-5-cyan-2-methyl-4-nitro-imidazol (67%). 

Im ersten Fall wird je nach Reaktionsbedingungen entweder 1,2-Dimethyl-5-(2-nitro-l,1,2-trimethyl-propyl )-imidazol (64%)976 oder 1,2-Dimethyl-5-(2-hydroxy-1,1,2-trimethyl-propyl)-imidazol (78%)977 als Hauptprodukt erhalten. Als Nebenprodukt entsteht /,2-Dimethyl-5-iso-propenyl-imidazol (16 bzw. 19%). 

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