Formamidines ureas

Formamidine-urea compounds (45) exchange imine fragments with primary amines (R4NH2) in non-protic solvents via the breakdown of the tetrahedral intermediate... 

Dipolar cycloaddition reactions, of nitrones to olefins, 46, 97 of 3-phenylsydnone, 46, 98 Dispiro[5.1.5.1]tetradecane-7,14-dione, photolysis to cyclohexylidene-cyclohexane, 47, 34 preparation from cyclohexanecarbonyl chloride and triethylamine, 47, 34 Displacement of bromine from 1-bromo-2-fluoroheptane to give 2-fluoro-heptyl acetate, 46, 37 N,N -Disubstituted formamidines from triethyl orthoformate and primary amines, 46, 41 N,N-Disubstituted thioureas from secondary amines and silicon tetra-isothiocyanate, 45, 69 N,N-Disubstituted ureas from secondary amines and silicon tetraiso-cyanate, 45, 69... 

When the less hindered 2,4-tolylene diisocyanate is reacted with a phospholene oxide catalyst linear oligomeric carbodiimides are obtained which have been reacted with a variety of nucleophiles to give poly(ureas), poly(acyl ureas), poly(formamidines) and poly-(guanidines) by addition across the N=C=N group. Also, reaction of the oligomeric carbodiimides with acrylic or methacrylic acid affords linear polymers, which can be further polymerized by free-radical type processes. Also, reaction of the carbodiimide oligomers obtained from 2,4-TDI with adipic acid in DMF produces a polyureid. ... 

Heterocycles Acetylacetone. N-Aminophthalimide. Boron trichloride. Dichloro-formoxime. Oicyanodiamide. Dicyclohexylcarbodiimide. Dietboxymethyl acetate. Diethyl oxalate. Diketene. Dimethylformaniide diethylacetal. Diphenyldiazomethene. Ethyl ethoxy-methylenecyanoacetate. Formaldehyde. Formamide. Formamidine acetate. Formic acid. Glyoxal. Hydrazine. Hydrazoic acid. Hydroxylamine. Hydroxylamine-O-sulfonic acid. Methyl vinyl ketone. o-Phenylenediamine. Phenylhydrazine. Phosphorus pentasullide. Piperidine. Folyphosphoric acid. Potassium diazomethanedisulfonate. Sodium ethoxide. Sodium nitrite. Sodium thiocyanate. Tetracyanoethylene. Thiosemicarbozide. Thiourea. Triethyl orthoformate. Tris-formaminomethane. Trityl perchlorate. Urea. Vinyl triphenyl-phosphonium bromide. 

Synthesis of Formamidines. N-(Benzylideneamino) heterocycles structurally transform into formamidines by inversion of the azomethine linkage. A series of formamidines related to l-(benzylideneamino)-imidazolidin-2-ones has been prepared by reaction of substituted formanilides with imidazolidin-2-one (ethylene urea) in thionyl chloride solution. The one-pot method which involves condensation between ethylene urea and an imidoyl chloride, represents a new method for the synthesis of trisubstituted formamidines (Chart VI). 

Hie cyclic anhydride (80.4) reacts with trimethylsilyi azide under anhydrous conditions to give a mixture of I,3-oxazine-2,6-dione isomers, which was used without further purification to synthesis several extended purines. Reaction with formamidine acetate in DMF in effect replaced the furandione ring by a pyrimidinone. Cyanamide produced a new fiued 2-aminopyrimidin-4-one [in (80.5, R = NH )], while urea led to a pyrimidinedione. Isatoic anhydride similarly yields 2-aminoquinazolin-4-one on treatment with cyanamide-DMF. 

Other synthons for 1,3-dicarbonyl compounds that have been successfully applied include p-chloro-a,P-unsaturated ketones and aldehydes, P-dimethylamino-a,P-unsaturated ketones (easily obtained from ketones by reaction with DMFDMA), P-alkoxy-enones"" and vinyl-amidinium salts."" Alkynyl-ketones react with 5-alkyl-isothioureas, giving 2-alkylthio-pyrimidines" and propiolic acid reacts with urea to give uracil directly in about 50% yield. "" 1,3-Keto-esters with formamidine produce 4-pyrimidinones"" and C-substituted formamidines with ethyl cyanoacetate give 2-substituted-6-amino -pyrimidinones. In analogy, pyrimidines fused to other rings, for example as in quinazolines, can be made from ortho-aminonitriles " and in general, from P-enamino esters. ... 

The mechanism and sequential steps of the overall reaction were presumed to occur by the base-catalyzed oligomerization of HCN, first to a dimer, and then to a trimer (amino-malonodinitrile) followed by the condensation of this trimer with formamidine to 4-aminoimidazole-5-carbonitrile (AICN) or the corresponding amidine (AICAI). The eyclization into adenine is completed by condensation of either AICN or AICAI with formamidine. Guanine and xanthine are formed by condensation of AICA with urea. ... 

The nitrogen of formamidine is presumably removed as ammonia and thus ends up in urea. Formate is bound to tetrahydrofolate as active formate or in general as an active Ci fragment (cf. Chapt. VI 5). 

Beside the above aryl amide macrocycles, one-pot intramolecular H-bond-directed macrocyclization reactions have also been demonstrated to work with macrocycles containing formamidine [13], urea [13, 76, 77], hydrazide [78], and Schiff-base [40, 79] linkages. Using naphthyridine-based building blocks (22a), Cuccia and coworkers synthesized macrocycles containing formamidine- (22b) and urea-linkages... 

Fig. 9.12 One-pot macrocyclization of naphthyridine diamine, forming macrocycles that contain urea (22b) and formamidine (22c) linkages...

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