Ring-fused derivatives imidazoles and

Trisubstituted imidazoles have been synthesized from 1,2-diketones or a-hydroxyketones with ammonium acetate in very short reaction times with excellent yields in the presence of l,l,3,3-VAr V ,(V -tetramethylguanidinium trifluoroacetate as an ionic liquid 06SC65 . Iodine acted as an efficient catalyst in the synthesis of 1,2,4,5-tetraarylimidazoles 93 using benzoin 91, 

A microwave-assisted, one-pot, two-step protocol was developed for the construction of polysubstituted 2-aminoimidazoles 101 via the sequential formation of imidazo[l,2-a]pyrimidinium salts from readily available 2-aminopyrimidines 99 and a-bromocarbonyl compounds 100, followed by opening of the pyrimidine ring with hydrazine 06OL5781 . A 

A basic ionic liquid, l-methyl-3-butylimidazolium hydroxide ([bmIm]OH) and l-butyl-3-methyl-methylimidazolium tetrafluoroborate ([bmim]BF4), has been introduced as a catalyst and reaction medium for the Markovnikov addition of imidazoles 116 to vinyl esters 115 under mild conditions to give imidazoesters 117 06JOC3991 06TL1555 . A series of (nitroimidazolyl)succinic esters and diacids were prepared from the Michael-type addition of the nitroimidazole to the a,P-unsaturated ester 06S3859 . 

A review on the synthesis and biological activity of vicinal diaryl-substituted 1H-imidazoles has been published 07T4571 . A focus review highlighted the recent progess in the catalytic synthesis of imidazoles 07CAJ568 . 

The synthesis of symmetrically and unsymmetrically substituted J ,J -diarylimidazolin-2-ones by copper-catalyzed arylamidation under microwave-assisted and conventional conditions was studied 07S1403 . Palladium-catalyzed direct functionalization of imidazolinone with aryl halides has been reported 07JA7768 . 

Bromo- and iodoimidazoles are useful intermediates for further functionalization. 4(5)-Aryl- I //-imidazoles 57 can be efficiently and selectively prepared by palladium-catalyzed Suzuki-Miyaura reaction of commercially available 4(5)-bromo-l//-imidazole 56 with arylboronic acids under phase-transfer conditions, which then underwent highly selective palladium-catalyzed and copper(I) iodide mediated direct C-2-arylation with a variety of aryl bromides and iodides under base-free and ligandless conditions to produce 2,4(5)-diaryl-l//-imidazoles 58 in modest to good yields 07JOC8543 . A new procedure for the synthesis of a series of substituted 2-phenylhistamines 60 utilizing a microwave-promoted Suzuki 

Imidazole-containing compounds have been utilized as reagents for various synthetic transformations. A convenient access to substituted allyl enol carbonates was established through the reaction of ketone enolates with the complex of allyl l//-imidazole-l-carboxylates 74 and boron trifluoride etherate 07JOC9372 . Relatively mild and highly efficient Cul-catalyzed /V-arylation procedures for imidazoles with aryl and heteroaryl bromides or chlorides have been developed in the presence of ligands 75 and cesium carbonate 07JOC2737 . a, -Unsaturated 2-acyl imidazoles 76 are an alternative and practical class of dienophiles for the DNA-based catalytic asymmetric Diels-Alder reaction in 

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Synthesis of Imidazoles and Ring-Fused Derivatives via Nitrogenation Strategy... 

Title Phenylethynyl and Styryl Derivatives of Imidazole and Fused Ring Heterocycles... 

It is easily possible to continue to insert nitrogen atoms into fused ring systems and some important compounds belong to these groups. The purines are part of DNA and RNA and are treated in Chapter 49, but simple purines play an important part in our lives. Coffee and tea owe their stimulant properties to caffeine, a simple trimethyl purine derivative. It has an imidazole ring fused to a pyrimidine ring and is aromatic in spite of the two carbonyl groups. 

Many ring-fused imidazole derivatives have been synthesized by various methods. Domino Michael addition retro-ene reaction of 2-alkoxyiminoimidazolidines and acetylene carboxylates provided a synthesis of 2,3-dihydroimidazo[l,2-a]pyrimidin-5-(l//)-ones <05T5303>. A single step synthesis of 3,5-dialkyl-9-nitroimidazo[l,2-c]quinazolin-2(3//)-ones from simple carbonyl compounds, primary amines or amino acid methyl esters and 2-azido-5-nitrobenzonitrile has been published <05TL5778>. Diels-Alder reaction of azadienes and benzimidazole-4,7-diones afforded imidazo[4,5-g ]quinoline-4,9-dione derivatives <05EJ01903>. Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of 4,5-diphenyl-l,3-dihydro-2//-imidazol-2-one provided a one-pot synthesis of 5//-imidazo[2,l-ft][l,3]oxazine derivatives <05T2645>. Microwave irradiation was employed in the synthesis of 1-ary 1-3-acetyl-1,4,5,6-... 

Related lactams such as (101), obtained by oxidation of substituted analogues of (99), undergo base-induced ring contraction (Scheme 22). Alternatively, conversion of the sulfones to the corresponding thioamides, followed by hydrazinolysis and cyclocondensation with carbonyldi-(imidazole), affords fused-ring triazolo derivatives <83EUP72029>. 

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