Imidazolones amino

On reaction with Li-HMDS 492 and subsequent treatment with MegSiCl 14 a-ketoesters such as 512 afford N-silylated Schiff bases such as 513, which can be reduced to amino acids 514 or amino alcohols 515 and dimerized with methanol or H2O to give the imidazolone 516 [95]. Analogous treatment of benzil with Li-HMDS 492 and quenching with Me3SiCl 14 gives 517, which reacts with the Li-enolate of methyl isobutyrate 498 at 78 °C in THF to give the adduct 518 in 75%... 

Azolo[l,8]naphthyridines. The reactions of the chloronaphthyridine 229 with o-phenylenediamine at 200 °C and with sodium azide in acetic acid give the fused-ring products 230 and 231, respectively (Scheme 54) <2003IJB192>. Amino acid-substituted naphthyridines can be cyclized to the fused imidazolones 232 upon treatment with phosphorus oxychloride and under microwave irradiation (Equation 62) <2002SC857>. Acylation of 2-hydrazino-naphthyridines followed by heating gives W-acyl compounds which are cyclized intramolecularly to the [l,2,4]tri-azolo[4,3- ][l,8]naphthyridines 233 (Scheme 55) <1996IJB106>. The same compounds may also be obtained from... 

Amino acids " " and aminobenzoic acids " " react as nitrogen nucleophiles to effect ring opening of unsaturated 5(4//)-oxazolones. Cyclization of the intermediate acylamino amide has opened the way for the synthesis of new series of imidazolones that now incorporate a carboxylic acid moiety into the N-1 substituent. These compounds are readily further elaborated into derivatives with diverse biological activity. 

Similarly, 4-(furan-2-ylmethylene)-2-phenyl-1 -substituted-5(477)-imidazolones 820, evaluated as antibacterial and antifungal agents, have been synthesized from the 4-(furan-2-yhnethylene)-2-phenyl-5(4//)-oxazolone 819 (Scheme 7.253). ° Using 4-arylmethylene-2-phenyl-5(4//)-oxazolones as substrates and 2-amino-5-methyl-l,3,4-thiadiazoles as nucleophiles the synthesis of the corresponding... 

Hydrolysis of the alkylated imidazolones 4 under alkaline conditions yields the chiral auxiliary, (5 )-1-phenylethanaminc and, after neutralization, the amino acid 5. Subsequent acetylation furnishes the crystalline A-acetyl-a-methyl-a-amino acids 6 in high enantiomeric excess4. 

The seemingly complex imidazolone (78-3) is in fact obtained in a single step by reaction of the amino-ester (78-1) with the iminoether (78-2) derived from capro-nitrile. The relatively acidic proton on the heterocyclic ring is next removed by reaction with sodium hydride. This anion is then alkylated with the same biphenyl-methyl bromide (77-2) that was used to prepare losartan to afford (78-4). The nitrile group is in this case converted to the tetrazole by means of tributyltin azide, a reagent that involves milder conditions than the traditional acidic medium used to generate hydrazoic acid. Thus, treatment of (78-4) with the tin reagent affords irbesartan (75-5) [82]. 

Amino-l,3,4-oxadiazoles (205) on treatment with cr-halogeno-ketones gave intermediate quaternary salts 206 that did not cyclize directly to imidazo[2,l-6]oxadiazoles (208) with base. Hydrolysis of 206 with aqueous potassium carbonate caused ring-opening at C-2 with subsequent closure to the imidazolone 207. These latter compounds could be cyclized to 208 with phosphorus oxychloride.204c 21 246... 

Amino-4(or 5)-A2-imidazolone [Glykocyami-din, 4 Oxo-2-imino-imidazolidin or Hydanto-inimid-(2), in Get], H2C-NH-C NH2,... 

Several other proteins show a low, but significant amino acid identity with atzA (Table 22.4). All of these, urease-alpha subunit (urea amidohydrolase), cytosine deaminase, and imidazolone-5-propionate hydrolase, catalyze hydrolytic reactions with substrates involved in the metabolism of nitrogenous compounds (Sadowsky et al 1998). A Rhizobium strain capable of atrazine dechlorination has been isolated from a soil that was previously treated with atrazine (Bouqard et al., 1997). This bacterium could not mineralize atrazine, and it accumulated hydroxyatrazine as the sole metabolite after long-term incubations. Interestingly, 22 of the 24 identified amino acids at the N-terminus of the atrazine halidohydrolase from Rhizobium were identical with atzA from Pseudomonas strain ADP. 

Asaro, M. F. Nakayama, I. Wilson, R. B. Formation of sterically hindered primary vicinal diamines from vicinal and geminal dinitro compounds. /. Org. Chem. 1992, 57, 778-782. Rodriguez, H. Marquez, A. Chuaqui, C. A. Gomez, B. Oxidation of mesoionic oxazolones by oxygen. Tetrahedron 1991, 47, 5681-5688. Heras, M. Ventura, M. Linden, A. Villal-gordo, J. M. Reaction of a-iminomethylene amino esters with mono- and bidentate nucleophiles a straightforward route to 2-amino-lH-5-imidazolones. Tetrahedron 2001, 57, 4371—4388. 

Quaternary oxazolium salts are easily cleaved by alkali iV-methylbenzoxazolium iodide affords iV-methyl-2-formamidophenol (135). iV-Methyloxazolium fluorosulfonates react with ethanolic ammonia to give imidazoles with sodium hydrogen sulfide, thiazolium salts are formed. Hydrolysis or aminolysis of 2-amino-lV-phenacyloxazolium salts (136) is followed by cyclization to yield imidazolones (137) or imidazoimidazoles (138), respectively (Scheme 5). 

Cyanourea will react similarly with an a-haloketone to give 1-cyanoimidazolin-2-ones, which are readily hydrolysed to the 1-carbamoyl and ultimately to the 77-unsubstituted analogues [46]. 4-Amino-2(2//)-imidazolones can be made from urea and an o-ketonitrile [47]. 

Diaminomaleonitrile derivatives 1112 are useful synthons for the synthesis of imidazoles (see CHEC(1984) and CHEC-II(1996)). For example, imidazolone 1115 is obtained from the reaction of 1,2-diaminomaleonitrile with isocyanate 1113 via the intermediate A -[(Z)-2-amino-l,2-dicycanovinylcarbamoyl]-/>-toluenesulfonamide 1114 (Scheme 269) <2001JHC939>. 

A number of attempts have been made to measure or calculate the relative stabilities of isomeric imidazoles, for example, fluoroimidazoles <88H(27)1803>, diazoimidazoles <87JMC357, 87JMC2222, 87JOC5538,90AHC(48)65>, nitro- and amino-imidazoles <89CJC1666,92JCS(Pl)2779>, 2-hydroxyimidazole, and 2-imidazolone <90JCS(P2)195>. 

A number of examples of imidazole synthesis from azirines and aziridines have been included under other classifications (see Sections 3.02.8.1.l(iii) and 3.02.8.1.2(i),(ii)). 2/f-Azirines are intermediates in the rearrangement of oximino p-toluenesulfonates to aminoketones in the presence of bases, and with 2-acylphenols these azirines form imidazolones. 4//-Imidazoles (244) are formed when a 2-amino-3,3-dimethylazirine reacts with an acetamide (Scheme 181) <90CHE719>. 

Metal-mediated approaches to the synthesis of imidazoles have been reported. PaUadium(ll)-catalyzed intermolecular 1,2-diamination of conjugated dienes with ureas led to 4-alk enyl-2-imidazolones in good yields rmder mild conditions <05JA7308>. Palladium-catalyzed cyclization of O-pentafluorobenzoylamidoximes 74 furnished l-benzyl-2-substituted-4-methylimidazoles 75 <050L609>. Direct copper(I)-chloride mediated reaction of nitriles 76 with a-amino acetals 77 followed by acidic reaction led to a variety of 2-substituted imidazoles 78 <05TL8369>. 

An azidocarbonyl group undergoes a thermally induced Curtius reaction to an isocyanate, and this reacts readily with a neighbouring primary or secondary amino group to form a fused imidazolone ring. Toluene or diphenyl ether may be used as solvent according to the temperature needed for the reaction to proceed in a reasonable time but without causing decomposition. 

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