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.
N,N,N′,N′-Tetraalkylchlorformamidiniumchlorides 1a, b react with ω-dimethylaminoalkylamines 19, 20 to give mixtures of N-(ω-dimethylammonioalkyl)-guanidinium salts 12, 13 and N-(ω-dimethylaminoalkyl)-guanidinium salts 21, 22. These mixtures are transformed to mixtures of the ureas 15, 17 and N-(ω-dimethylaminoalkyl)-guanidines 23, 25 on treatment with aqueous sodium hydroxide. The reaction of N-(3-dimethylammoniopropyl)-guanidin 25a with dimethylsulfate in a molar ratio of 1:1 delivers a mixture of the N-(3-dimethylaminopropyl)-N,N,N′,N′,N″,N″-pentamethyl-guanidinium salt 29a and the N-(3-dimethylammoniopropyl)-N,N′,N′,N″,N″-pentamethyl-guanidinium-bis (methylsulfate) 33a. The action of dimethylsulfate on the guanidines 23a, 25a in a molar ratio of 2:1 affords the bisquarternary salts 32a, 33a. Alkylating reagents as methyliodide, benzylbromide, allylbromide and chloroacetonitrile attack N-(2-dimethylaminoethyl)-N′,N′,N″,N″-tetraethylguanidine (23b) in a molar ratio of 1:1 cleanly at the dimethylaminoethylgroup to give the ammonium salts 30a–d. As a strong base the guanidine 23b dehydrochlorinates β-Chlorpropionitrile and chloroacetone under formation of the guanidinium salt 21c. In contrast to this the reaction of ethyl bromoacetate with the N-(2-dimethylaminoethyl)guanidine 23b occurs at the guanidinogroup giving the guanidinium salt 28c. The methylation of the guanidinium chlorides 21a, 22a with dimethyl sulfate affords the bis-quaternary salts 35b, 36b with mixed anions. From the heterocyclic guanidines 14, 16 and the alkylating reagents benzylbromide and ethyl bromoacetate the heterocyclic guanidinium salts 37a, b, 39a, b can be obtained. The reactions with ethyl chloroformiate proceed in an analogous way giving the guanidinium salts 37c, 39c. The N-alkyl-N,N,N′,N′-tetramethyl-(3-ureidopropyl)guanidinium salts 41a, b can be prepared from the N′,N′,N″,N″-tetramethyl-N′′-(3-ureidopropyl) guanidine 17a and the alkylating compounds dimethyl sulfate and benzyl bromide. Several compounds obtained that way were transformed to the corresponding tetraphenyloborates and bis(tetraphenylborates), respectively.
Bis[bis(dibutylamino)methylen]hydrazine 8 is prepared from N,N,N′,N′-tetrabutylchloroformamidinium chloride (4c) and hydrazine. Bromine transforms 8 to the heterocyclic guanidinium salt 15a which is isolated as tetraphenylborate. From N,N,N′,N′-tetraalkylchloroformamidiniumchlorides and ethylendiamine the diguanidines are prepared which are alkylated to give diguanidinium salts, From these salts guanidinium salts can be prepared by anion metathesis with tetraphenylborate-, iodide-, hexafluorphosphate-, trifluoromethansulfonat-, bis(trifluormethansulfonyl)imide and tricyanmethanide as counteranions. The structure of the compounds 15 and 17b is confirmed by crystal structure analyses.
Cyclopropylacetylene and N,N,N′,N′,N′′,N′′-hexamethylguanidinium chloride (1a) react to give the orthoamide derivative 8c, in the presence of sodium hydride. 8c is transformed by elemental iodine to the vinylogous guanidinium salt 6f. Anion metathesis with the salts 5a, 5e, 6g delivers vinylogous guanidinium salts 5e–5i, 12a with counter ions derived from carbon acids (tricyanomethane, 1,1,3,3-tetracyano-propene). Phenylogous amidinium salts 15 guanidinium salts 19, 21 and the phenylogous orthoamide derivatives of formic acid 18 and carbonic acid 33 have been prepared.