Tetrahydropyrimidines synthesis

Tetrabenazine, 350 Tetracaine, 10 Tetracycline, 212, 213 A -Tetrahydrocannabinol, 394 Tetrahydropyrimidines, synthesis, 266... 

Taclamine, 224 Talampicillin, 438 Talopram, 357 Tamoxifen, 127 Tandamine, 347, 460 Tazolol, 110, 268 Teclozan, 28 Temazepam, 402 Terodiline, 56 Tesicam, 379 Tesimide, 296 Testolactone, 160 Tetrahydropyrimidine synthesis, 303 Tetrahydroquinoline synthesis, 371 Tetrazole synthesis, 301,... 

Bazureau et al. have reported a similar protocol to that described in Sect. 8.1 for the rapid synthesis of 2-thioxo tetrahydropyrimidin-4-(lH)-ones via cycli-zation of a primary amine with an isothiocyanate and a /1-dielectrophile (Fig. 35) [138]. First a j6-amino ester was linked to the ionic hquid support... 

The key step in the synthesis was bromination of ketone 59, followed by hydrogenation to liberate the free guanidine, which underwent an intramolecular Sn2 reaction to form the tetrahydropyrimidine ring B. Further hydrogenation reduced the ketone to yield 42% of 63 containing the fully functionalized tricyclic system and protected hydroxymethyl-uracil side chain of cylindrospermopsin. Hydrolysis of the pyrimidine of 63 in concentrated hydrochloric acid at reflux and selective monosulfation completed the synthesis of cylindrospermopsin. 

A simple, efficient and modified Biginelh procedure was developed by Shah and co-workers [93] for the synthesis of tetrahydropyrimidines 44 by a solvent and catalyst-free condensation of a 1,3-dicarbonyl compound, an aryl aldehyde and (thio)urea applying microwave irradiation. The desired compounds 44 were obtained in short reaction times and in better yields compared to conventional heating (Scheme 33). 

Khunt RC, Akbari JD, Manvar AT et al (2008) Green chemistry approach to synthesis of some new trifluoromethyl containing tetrahydropyrimidines under solvent free conditions. Arkivoc (xi) 277-284... 

Muravyova EA, Desenko SM, Musatov VI et al (2007) Ultrasonic-promoted three-component synthesis of some biologically active 1, 2, 5, 6-tetrahydropyrimidines. J Comb Chem 9 797-803... 

Anthranil amide is also readily cychzed with carbon disulfide in pyridine to l,2,3,4-tetrahydroquinazolin-4-one-2-thione (XXXVII, m.p. 282° C) 159). Using a -amino thiocarbonamide instead of a -amino carbonamide yields condensed l,2,3,4-tetrahydropyrimidine-2,4-dithio-nes. An example is the synthesis of 4,5,6,7-tetrahydro-lH-pyrazolo-[3,4-d]pyrimidine-4,6-dithione (XXXVIII m.p. >26O°C) from 4-thio-carbamoyl-5-aminopyrazole 159). 

Chloronicotinoyl chloride 95 was used as the starting compound in the synthesis of hetaryl annulated 1,6-naphthyridines. Its reactions with 4,5-dihydro-1//-imidazolines 96a or tetrahydropyrimidines 96b gave the corresponding A-acyl derivatives 97a,b, which underwent cyclization with potassium Arf-butoxide to yield imidazo- 98a or pyrimido[l,2-gr[[l,6]naphthyridinones 98b, respectively. Compounds 98a,b exhibit antiallergic and anti-inflammatory activitives (1990JHC189, 1990USP5070086). 

A new synthetic route to 2-aryl-A-tosyl azetidines 14 has been developed starting from A-tosylarylaldimines in two steps in an overall yield of 63-70%. A formal [4+2] cycloaddition of these 2-aryl-A-tosylazetidines with nitriles in the presence of Bp3.0Et2 has been described for the synthesis of substituted tetrahydropyrimidines 15. It is proposed that the reaction proceeds in a Ritter fashion <04OL4829>. 

A practical synthesis of 2//-pyrimido[4,5-e]ll,2,4]triazin-3-ylidenecyanamides 106 has been developed. The key step is the coupling reaction of an aryldiazonium salt with l-cyano-3-(2,6-dioxo-l,2,3,6-tetrahydropyrimidin-4-ylamino)-2-methylisothiourea 105, obtained from uracil 104, followed by an intramolecular cyclization <04TL931ft>. 

During their work on the total synthesis of diazasteroids, Burckh lter and Abramson8 investigated, as a model, the synthesis of 2-(2-ethoxy-carbonylethyl)-3,4,5,6-tetrahydropyrimidine hydrochloride (16) via the condensation of 1,3-propanediamines (14) with ethyl 3-ethoxycarbonyl-propionimidate hydrochloride (13). When 16 was heated above its melting point, and the melt was allowed to sublime, 2,3,4,6,7,8-hexa-hydro-6-oxopyrrololl,2-a]pyrimidine hydrochloride (17) was isolated in excellent yield [Eq. (3). ... 

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