2-chloro-1,3,dimethylimidazolium chloride

The standard route to sydnones is the cyclodehydration of iV-nitroso-P-amino acids. 2-Chloro-4,5-dihydro-13-dimethylimidazolium chloride 97 has been shown to be an excellent reagent for this conversion, as, for example, in the synthesis of 3-phenylsydnone 98 <99JOC6989>. Functional group manipulations of fused sydnones have led to the isolation of several new compounds including 99 and 100 <99H(51)1433>. 4-Acetylsydnones react with hydrazine at room temperature to give 2,4-dihydropyrazol-3-ones 101 <99H(51)95>. ... 

The 2,3,5,6-tetrahydro-imidazo[l,2- ]imidazole system 40, a bicyclic guanidine, has been prepared by treatment of the 2-(2-hydroxyethylimino)imidazolidine 39 with 2-chloro-l,3-dimethylimidazolium chloride (CDIC) (Scheme 27) C2000JOC7779, CHEC-III(11.04.9.1.4)159>. 

Reports from Kuhn and co-workers identified the reaction of stable car-benes with 1,2-dichloroethane to yield 2-chloro-l,3-disubstituted imidazo-lium chloride salts.58 The versatility of these salts has been demonstrated by Ishikawa and co-workers.59 Due to its strong electrophilicity, 2-chloro-l, 3-dimethylimidazolium chloride can be used in chlorination, oxidation, reduction and rearrangement reactions, in addition to being used as a dehydrating agent. 

Chloro-l,3-dimethylimidazolium chloride (DMC) [26] (R =R = Me, L = H in 11, Scheme 4.8a) not only acts as a powerful dehydration agent but also has unique and versatile abilities to chlorinate primary alcohols, to oxidize primary and secondary alcohols and to reduce sulfoxides and so on. In addition, DMC easily reacts with amines to yield the corresponding guanidines. Thus, methods of preparing monocyclic and bicyclic systems by application of DMC chemistry in the key steps have been developed [27] the reaction of DMC-type chloroamidine compounds with amines for trisubstituted mono-cyclic guanidines [27a] (Scheme 4.8a), the intramolecular cyclization of thiourea derivatives after activation with DMC for monosubstituted or disubstituted monocyclic and bicyclic guanidines [27b] (Scheme 4.8b), and the DMC mediated cyclization of... 

Another unusual SnAt reaction of fused trifluoromethylchloropyrimidines was disclosed in a course of human adenosine A2A receptor antagonists discovery [742], This is the reaction of aroylation of 2-chloro-4-trifluoromethylthieno[3,2-d]pyrimi-dine 1201 by aldehyde incorporation catalyzed by N,N-dimethylimidazolium chloride affording the ketoaryl compound 1202. The process based on SnAt reaction of zwitterionic intermediate 1203 with followed dimethylimidazolium elimination. Unfortunately the exact procedures does not refer in original paper but reported in Vemalis patent (Scheme 258) [743],... 

Scheme 30. Reagents and conditions a) TMSOTf, CH2CI2, 0°C, 47% b) PhsP, PhH, H2O c) octadecanoic acid, 2-chloro-l,3-dimethylimidazolium chloride, PhH. 80% d) NBU4F, CH3CN e) MeONa, MeOH then water, 87%.

Friedel-Crafts reaction of arenes with a-chloro-a-(methylthio)acetophenones [19], When A -phenylbenzimidoyl chlorides are aroylated with an aryl halide in the presence of a catalytic amount of an azoliuni salt (such as 1,3-dimethylimidazolium iodide) and sodium hydride, followed by acid treatment in TUF, unsymmetrical benzils can be isolated in 80-92% yields [201. Added to this method is the sequence ketone enaminoketone a-diketone, which cleaves a carbon-carbon double bond in the final stage by photooxygenation [21]. 

When 1 -methylimidazole is quaternized at N-3 by 4-methoxybenzyl chloride, the salt deprotonates readily in the presence of sodium hydride in DME. 1,3-Dimethylimidazolium salts react analogously, allowing access to 2-chloro-, 2-bromo-, 2-deutero-, and various 2-substituted phosphorus- and sulfur-containing imidazoles <8877413>. 

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