1.3- Imidazolidin-5-ones alkylations

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, 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... 

Nitrone cycloaddition reactions with alkynes have been widely used for the synthesis of imidazolidine nitroxides (736) and (737), containing chelating enam-ino ketone groups (821). Different heterocyclic systems were obtained, such as 3-(2-oxygenated alkyl)piperazin-2-ones (738) (822), also compounds containing the isoxazolo[3,2-i]indole ring system (739) (823) and a new class of ene-hydroxylamino ketones- (l )-2-( 1-hydroxy-4,4,5,5-tetraalkylimidazolidin-2-ylidene)ethanones (740) (824) (Fig. 2.46). 

Reductive cleavage of imidazolidines 641 was implicated in the one-pot synthesis of N,N,N -trisubstituted ethylenediamines 643 from V,V -disubstituted ethylene diamines and an aldehyde R CHO. Presumably the intermediate iminium ion 642 is reduced by NaBH4 (Scheme 154) <2003SC3193>. Naphthalene-catalyzed lithiation of l,3-dimethyl-2-phenylimidazoline 644 leads to benzylic C-N bond cleavage. The intermediate dianion can be trapped with electrophiles (HjO, alkyl halides, ketones, and aldehydes) to afford diamines 645 <2005T3177>. 

In DMF, benzalazine (VII) shows two, one-electron steps in CV. Preparative reduction of VII in the presence of an alkylating agent yields alkylated bis-hydrazines (VIII) or the dialkylated hydrazone (IX) [51], as in Eq. (14). An assignment of the stereochemistry of the bis-hydrazones, obtained by reduction of VII followed by protonation, could be achieved by cyclization with aldehydes to imidazolidines. 

Moss et al. succeeded in producing imidazolidine 517 by a one-pot procedure involving alkylation of N,A -dimethylethylenediamine with 1-bromo-l-phenyldiazirine, carbene generation, and subsequent cyclization (84TL1023). Rh2(OAc)4-catalyzed composition of diazo uracils 518 affords good yields of imidazolidinones 519 via carbenoid ring contraction... 

Even though the most widely used preparation is still the reaction of alkali isothiocyanates or alkyl and aryl isothiocyanates with a-amino carboxylic acid derivatives, the reaction of dithiocarbamic acid esters (CCX) with a-amino carboxylic acids (CCXI) has certain advantages especially in the synthesis of heterocyclically substituted imidazolidin-4-one-2-thiones (221). 

The reaction product of 2-amino-2-deoxy-D-glucopyranose (87) with alkyl or aryl isocyanates or isothiocyanates were previously assigned the structure of l,2-dideoxy-D-glucopyrano[l,2-rf]imidazolidin-2-ones (89, Z =... 

The enolates of //-acylimidazolidinones derived from 1.131 generated from ephedrine 1.61 (R = H) are useful in asymmetric alkylations [447, 448] and aldol reactions [449, 450] and cuprate additions to the a,p-unsaturated acyl analogs have recently been described [451], These chiral auxiliaries are cleaved by MeONa/MeOH or LiEtBHj. Recently, Davies and coworkers have suggested the use of symmetrical AyV-diacyl-1,3-imidazolidin-2-ones 1.132, formed from diamines having a C2 axis of symmetry [452], for asymmetric aldol reactions [449]. Juaristi [453] has used peihydropyrimidin-4-ones for related purposes. 

An analysis of the NMR spectra of a large series of 1,3-di- and 1,2,3-trisubstituted imidazolidines with aryl, alkyl and aralkyl groups performed by Perillo et aV yielded a set of H-C couplings including those across one bond. The differences in the coupling values have been interpreted by the authors in terms of inductive substituent effects and a lone pair orientation. 

Imidazolines.— The double Michael addition of 1,2-diamines to allenic or acetylenic nitriles provides a convenient route to imidazolines (Scheme 105). Imidazolines are also available from di-immonium dibromides and N-alkyl- or JV-aryl-amidines. Imidazolidin-2-ones are obtained by anodic addition of 1,3-dimethylurea to hexa-2,4-diene and related derivatives. 

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