Imidazolidin-4-ones

Similar alkylations may be effected on oxygen. l-(2-Chloroethyl)imidazolidin-2-one (312) when treated with potassium hydroxide or sodium hydride underwent ring closure to the tetrahydroimidazo[2,l-6]oxazole (313) (57JA5276). This approach can be used for the preparation of bicyclic hydantoins and the corresponding dihydro derivatives of (313) using the mesylate of (312) and NaH (77JHC5U, 79JMC1030). 

Imidazolidin-2-one, 4,5-diacetoxy-4,4-di(p-bromophenyl)-reactions with urea, 5, 406... 

Imidazolidin-2-one, 4,5-dihydroxy-4,4-di(p-bromophenyl)-reactions with urea, 5, 406 Imidazolidin-2-one, 1,3-divinyl-polymerization, 1, 280 I midazolidin-2-one, 1 -ethyl-3-vinyl-polymerization, 1, 279 Imidazolidin-2-one, 4-methylene-synthesis, 5, 140... 

Imidazolidin-2-one, l-(5-nitro-2-thiazolyl)-pharmacological activity, 6, 328 Imidazolidin-4-one, l-aryl-3-phenyl-2-thioxo- C NM S, 355 Imidazolidinones C NMR, 5, 355 Imidazolidin-2-ones nucleophilic displacement, 5, 428 polymers, 1, 279-280 reactivity, 5, 376 synthesis, 5, 466, 471 Imidazolidin-4-ones synthesis, 5, 468 Imidazoline, 2-alkyl-synthesis, 5, 463 Imidazoline, 2-amino-applications, 5, 498 Imidazoline, 2-aryl-synthesis, 5, 463 Imidazoline, 2-methyl-synthesis, 5, 487 Imidazoline, 2-nitroamino-synthesis, 5, 471 2-Imidazoline, 2-arylamino-tautomerism, 5, 368 2-Imidazoline, 1-benzyl-methylation, 5, 425 2-Imidazoline, 1,2-diaryl-synthesis, 5, 463... 

Bicyclic imidazolidin-2-ones 173 have been prepared in good yields and high diastereoselectivity (Scheme 5.46) [51], The ring closure of MAT -disubstituted ureas 172 was catalysed by [AuCl(lPr)] complex in presence of a silver salt. 

Other degradation products of the cytosine moiety were isolated and characterized. These include 5-hydroxy-2 -deoxycytidine (5-OHdCyd) (22) and 5-hydroxy-2 -deoxyuridine (5-OHdUrd) (23) that are produced from dehydration reactions of 5,6-dihydroxy-5,6-dihydro-2 -deoxycytidine (20) and 5,6-dihydroxy-5,6-dihydro-2 -deoxyuridine (21), respectively. MQ-photosen-sitized oxidation of dCyd also results in the formation of six minor nucleoside photoproducts, which include the two trans diastereomers of AT-(2-de-oxy-/j-D-eryf/iro-pentofuranosyl)-l-carbamoyl-4 5-dihydroxy-imidazolidin-2-one, h/1-(2-deoxy-J8-D-crythro-pentofuranosyl)-N4-ureidocarboxylic acid and the a and [5 anomers of N-(2-deoxy-D-eryfhro-pentosyl)-biuret [32, 53]. In contrast, formation of the latter compounds predominates in OH radical-mediated oxidation of the pyrimidine ring of dCyd, which involves preferential addition of OH radicals at C-5 followed by intramolecular cyclization of 6-hydroperoxy-5-hydroxy-5,6-dihydro-2 -deoxycytidine and subsequent generation of the 4,6-endoperoxides [53]. 

Kim and Varma have described the preparation of a range of cyclic ureas from diamines and urea [366]. In the example highlighted in Scheme 6.203, ethylenedi-amine and urea were condensed in the presence of 7.3 mol% of zinc(II) oxide in N,N-dimethylformamide as solvent at 120 °C to furnish imidazolidin-2-one in 95% isolated yield. Key to the success of this method is that the reaction needs to be performed under reduced pressure in order to remove the ammonia formed from the reaction mixture. This method was extended to a variety of diamines and amino alcohols [366]. 

Other tetrahydroimidazoles have been obtained from the reaction of 2-amino-2-deoxyhexoses with isocyanates and with thiocyanates. Thus, 2-amino-2-deoxy-D-glucopyranose hydrochloride (78) reacts readily with phenyl isocyanate to yield77 the corresponding 4,5-D-glucopyrano-l-phenyl-4-imidazolidin-2-one (79). Alternatively, the tetraacetate 80 was converted into the urea derivative 81, the prod-... 

Cyclic amides can be used similarly to the thioamides of the last section. l-(2-Chloro-ethyl)imidazolidine-2-one (64) with potassium hydroxide gave the tetrahydroimidazo[2,l-fc]oxazole (65) (57JA5276). 

Table 8 Analytical and Relevant Spectroscopic Data for Imidazolidin-2-ones 30 791...

N2CHC02R, cat Rh2[2-pyrrolidone-5-carboxylate]-polymer (enantioselective) N2CHCQ2R, cat Rh2[Me 1 -(3-phenylpropanoyl)-imidazolidin-2-one-4-... 

Acyclic ureas have been obtained in moderate yield (up to 66%, after 20 h) by the thermal decomposition of carbamate salts (RNH3)02CNHR at high temperature (453 K), without the use of a catalyst [127a, b]. At high temperatures and pressures, diamines can also react with C02, in the absence of a catalyst, to afford cyclic ureas (imidazolidin-2-ones, tetrahydro-pyrimidin-2-ones) in moderate to good yield and selectivity [69c, 127c]. 

An extension of the above method for the preparation of cyclic ureas (imidazolidin-2-ones) was developed by the same group [63], by employing carbon dioxide/methanol in place of a carboxylic acid, and the UDC strategy. Additionally, treatment of the Ugi-5CR products with base afforded hydantoins in good yield. 

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