N-(ω-Dimethylammonioalkyl)-N´,N´,N´´,N´´-tetramethylguanidinium-dichlorides 5a, b are obtained from the chloroformamidinium salt 2 and diamines 3a, b. Their crystal structures reveal that the guanidinium ions are associated with the chloride ions via N-H· · ·Cl hydrogen bonds. By deprotonation of 5a, b with one equivalent of sodium hydroxide, the guanidinium chlorides 4a, b are accessible, and a further deprotonation leads to the aminoguanidines 6a, b, which hydrolyze in the presence of excessive aqueous sodium hydroxide to give the aminoalkylureas 7a, b.
The salts 9a, b and 10a, b were synthesized from 4a, b and 5a, b, respectively, by anion metathesis by means of sodium tetraphenylborate. 7a reacts with dimethyl sulfate to give the waxy ammonium salt 11a, which was converted to the crystalline tetraphenylborate salt 12a. The crystal structures of all the tetraphenylborates were determined by single-crystal X-ray diffraction analysis.
The C-glycosyl alkynecarboxylic acid orthoamides 22 and 23 are proposed as versatile precursors for the synthesis of new types of C-nucleoside analogs. The new synthetic strategy includes alkynylation of protected aldoses 13 or ketoses by Grignard ethynylation or Barbier propargylation, O-protection of the resulting alkynols 14-16, and nucleophilic addition of the metalated protected terminal alkynes 20 and 21 to peralkylguanidinium salt 2 to afford the corresponding alkynecarboxylic acid orthoamides 22 and 23, which in reactions with mono or bis-nucleophiles could serve as building blocks for the construction of a wide variety of C-nucleoside-like binary conjugates. All the steps are demonstrated on 2,4,3,5-bis(4-methoxybenzylidene)-protected L-xylose 11 as a model compound. The synthesis of a representative series of C-glycosidic conjugates of highly substituted “push-pull” 1,3-butadienes 32-35, pyrimidines 24-31, and 2-pyridones 36-39 is included. The stereochemistry of all described compounds is established by 2D-NMR techniques. A general character of the proposed synthetic strategy, when applied to different appropriately protected sugar derivatives, is suggested, and a biomedical applicability of the described type of conjugates is expected.
Aryl formates 4a-u, 6 , 8 , 10, 12, 14, 16, 18, 20, 22, 24, 26 are prepared by formylation of hydroxyarenes 3a-u, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 with N,N-diformylacetamide (1) or triformamide (2), respectively, in fairly good yields. The reactions can be catalyzed by sodium diformamide or praseodymium(III) triflate. The thiolformate 28 was obtained analogously from 1-thionaphthol (27).
The alkylammonium alkylcarbamates 2, 4a,b, 14 were prepared from the amines 1, 3a,b, 13 and CO2. The crystal structures of 2 and 4b show carbamate anions, which are connected by N-H···O hydrogen bonds to form centrosymmetric dimers. The zwitterionic carbamates 7a,b, 8a,b and 11 are formed in the reactions of the diamines 6a,b and 10 with CO2. The crystal structures of 7a and 8b show strong intermolecular hydrogen bonds involving water molecules, the ammonium and the carbamate groups. In these compounds the molecules are interconnected in an extended two- or three-dimensional network. Due to the absence of crystal water molecules, the structure of 11 contains intermolecular hydrogen bonds involving the ammonium and the carbamate group in double-stranded chains. The diamines 17a,b react with CO2 to give the zwitterionic carbamates 18a,b.
1,3-Dimethyl-5-imino-imidazolidine-2,4-dione (7a) undergoes thiolysis (H2S) to give the corresponding imidazolidine-2,4-dione-5-thione derivative 6. The 5-N-methylimino analogue 7b can be obtained from 7a by methylation. Further methylation of 7b affords the crude iminium salt 8c from which the heterocyclic orthoamide derivatives 10, 11 can be prepared. The heterocyclic amide acetal 9a can be obtained from 7a and dimethyl sulfate in methanol and subsequent addition of sodium methanolate in a one-pot reaction. The aminal ester 10 is converted to the amide acetal 9a on treatment with hydrogen chloride in methanol
The Residual Volume Approach (RVA), a recently developed method for the prediction of fundamental physical properties of ionic liquids (ILs) is extended and now allows the estimation of ionic conductivity of unknown ILs, using a simple linear correlation between the ionic conductivity and previously defined substituent parameters - βx. The proposed method is applied to the conductivity correlations of 61 n-alkyl substituted imidazolium, tetraalkylammonium, pyrrolidinium, piperidinium, sulfonium and phosphonium homologous ILs, containing [BF4]−, [Tf2 N]−, [C2 F5PF]−, [CF3BF3]−, [C2H5BF3]−, [F(HF)2.3]−, [Br]−, [I]−, and [formate]− as anions. The influence of the ion type - both anion and cation - on the property changes is discussed. Moreover, it is shown that relatively rigid cations with C2 symmetry decrease the expected conductivity in the same manner as they increase the viscosity of the ILs.
2,5-Dimethyl-1,3,4-thiadiazole (1a) reacts which aromatic carboxylic acid esters 8a - u in the presence of excessive sodium hydride under condensation to give sodium enolates which afford on hydrolysis the phenacyl-1,3,4-thiadiazoles 9a - u. The action of aromatic carboxylic acid chlorides on 1a in the presence of triethylamine gives rise to the formation of mixtures of diacylated thiadiazole derivatives 16 and 18. In some cases the pure 3-acyl-phenacylidene-2,3-dihydro-1,3,4-thiadiazoles 16 can be isolated. Generally the compounds 16 are rearranged on heating in higher boiling solvents to give the enolbenzoates 18. Hydrolysis of the diacylated thiadiazoles 16 and 18 yields the phenacylthiadiazoles 9a, c, d, g - j, v, w.
β-Ionone and camphor were ethynylated to give the alkynols 14, 16, 17 which can be transformed to the alkynolethers 5b, 5i, 5j, 5k, 5l, 5m by treatment with dimethylsulfate and chlorotrimethylsilane, respectively. From the alkynolethers 5h, 5i, 5j/5k, 5l/5m the orthoamide derivatives 4h, 4i, 4j/4k, 4l/4m can be prepared by treatment with N,N,N′,N′,N″,N″-hexamethylguanidinium chloride (8) in the presence of sodium hydride. The orthoamides 4h, 4i react with the sulfonamide 30 under condensation yielding the N-sulfonylated acrylamidines 31, 32. From the orthoamide 4h and p-nitroaniline the propiolamidine 29 could be obtained. The orthoamides 4j/4k and 4l/4m, react with benzamidine to give the pyrimidines 33, 34, respectively. In the reaction of malonodinitrile (9a) with the orthoamides 4i and 4j/4k, mixtures of 1,1-diamino-1,3-butadienes 36, 38 and 1,3-diamino-1,3-butadienes 37 and 39 are produced, respectively. From CH2-acidic compounds as ethylcyanacetate (9b), diethyl-malonate (9c) and nitromethane (9d) and the orthoamide 4i the 1,1-diamino-1,3-butadienes 36b–d were produced. The pyridone derivative 40 can be prepared from cyanoacetamide (9e) and the orthoamide 4i. The condensation of the orthoamides 4j/4k with cyanoacetamide (9e) affords a mixture of the pyrimidone 41 and the nicotinonitrile 42.