Guanidines structure

Various guanidine structures were synthesized which lacked the imidazole ring, but none had the desired antagonist activity, demonstrating that both the imidazole ring and the guanidine group were required. 

The chain was now extended from a two-carbon unit to a three-carbon unit to see what would happen if the guanidine group was moved further away from the imidazole ring. The antagonist activity increased for the guanidine structure (Fig. 13.18), but... 

Pinacidil [60560-33-0], antihypertensive, vasodilator, potassium channel activator, 192. Either DCC or phosgene in the presence of ethyldiisopropylamine can be used to generate the substituted guanidine structure from the substituted thiourea [139-143]. 

Among the useful diuretics, the unique characteristic of amiloride and related pyrazinoylguanldines is the strong basic property. Other diuretics are acids or weak bases. Amiloride has a pK of approximately 8.7 This strong basic character Is attributed to the guanidine structure. Triamterene is a weak base with a pK of 6.2. 

The growth centers from carbodiimides are formed through the reaction with an alkali salt, and have the guanidine structure (Equation 7.20). These systems are a part of hquid single-component initiation systems of anionic polymerization of lactams [47]. 

The methacrylic backbone structure makes the spherical Toyopearl particles rigid, which in turn allows linear pressure flow curves up to nearly 120 psi (<10 bar), as seen in Fig. 4.45. Toyopearl HW resins are highly resistant to chemical and microbial attack and are stable over a wide pH range (pH 2-12 for operation, and from pH 1 to 13 for routine cleaning and sanitization). Toyopearl HW resins are compatible with solvents such as methanol, ethanol, acetone, isopropanol, -propanol, and chloroform. Toyopearl HW media have been used with harsh denaturants such as guanidine chloride, sodium dodecyl sulfate, and urea with no loss of efficiency or resolution (40). Studies in which Toyopearl HW media were exposed to 50% trifluoroacetic acid at 40°C for 4 weeks revealed no change in the retention of various proteins. Similarly, the repeated exposure of Toyopearl HW-55S to 0.1 N NaOH did not change retention times or efficiencies for marker compounds (41). 

A new protein of unknown structure has been purified. Gel filtration chromatography reveals that the native protein has a molecular weight of 240,000. Chromatography in the presence of 6 M guanidine hydrochloride yields only a peak for a protein of M, 60,000. Chromatography in the presence of 6 M guanidine hydrochloride and 10 mM /3-mercaptoethanol yields peaks for proteins of M, 34,000 and 26,000. Explain what can be determined about the structure of this protein from these data. 

The reaction of diacetylene or its monosubstituted homologs with guanidine in the presence of an equimolar amount of sodium ethylate (80°C, EtOH, 14 h) leads to 2-amino-4-alkylpyrimidines (33) (70ZOR1347 71ZOR14). Their structures were proved by comparison of their properties (as well as those of their picrates) with those of authentic samples obtained by independent synthesis. 

Ultraviolet spectral comparisons indicate that structure 107 predominates over 108 when R = H or OH, but that 107 is the predominant form when R = aryl. - Similarly, 109 predominates over 110 by a large factor when R = H, OH, or Me, and by a smaller factor when R is a higher alkyl group, but 110 predominates when R is an aryl group. (For a discussion of guanidine derivatives corresponding to 110, see reference 110.)... 

The guanidine function, when attached to an appropriate lipophilic function, often yields compounds that exhibit antihypertensive activity by means of their peripheral sympathetic blocking effects. Attachment of an aromatic ring via a phenolic ether seems to fulfill these structural requirements. Alkylation of 2,6-dichlorophenol with bromochloroethane leads to the intermediate, 58. Alkylation of hydrazine with that halide gives 59. Reaction of the hydrazine with S-methylthiourea affords the guanidine, guanoclor (60). ... 

Thereafter, molecules have been synthesised with a bicyclic ring, such as a quinoleine or an indole, inserted. Many of these compounds like zoniporide and BMS-284640 are selective NHE1 inhibitors, but some inhibit also other isoforms. Most recently, an additional group of compounds with 4-substituted (benzo[b]thiophene-2-carbonyl) guanidines has been synthesised and these are potent NHE1 inhibitors. A structurally distinct compound, S-3226, was found to be the first selective NHE3 inhibitor. 

When cyanogen bromide was used instead of CS2, the corresponding guanidines 169 were obtained under analogous conditions [108]. Moreover, differently substituted guanidines 171 could be obtained in very good yields when the isothiourea 168 was alkylated with Mel under microwave irradiation and the product treated with a primary amine. An intramolecular version of this reaction was also described for the preparation of structure 172 present in several important natural products (Scheme 61). 

ET-IR spectroscopy was employed to investigate the structures of the 1 1 complexes between Li" and the guanidine-substituted azo compounds pyiidine-2-azo-p-phenyltetramethylguanidine and 4,4 -bis(tetramethylguanidine)azoben-zene. Both Li" complexes exist as dimers in acetonitrile solution.The structural chemistry of potassium N,N -di(tolyl)formamidinate complexes has been investigated in detail. These compounds were prepared by deprotonation of the parent Af,N -di(tolyl)formamidines with potassium hydride (Scheme 13). The resulting adducts with either THE or DME display one-dimensional polymeric solid-state structures that exhibit /r-fj fj -coordinated formamidinates. 

Especially notable is also the synthesis and structural characterization of an unusual antimony(III) guanidinate. 1,2,3-Tiiisopropylguanidine, Pr N = C(NHPr )2,was found to react with 1 molar equivalent of Sb(NMe2)3 in toluene under formation of a yellow solution, from which the novel compound Sb[Pr NC(NPr )2][Pr NHC(NPr )2] could be isolated in 10% yield as highly air-sensitive crystals. In the solid state, the complex adopts a heavily distorted trigonal-bipyramidal molecular structure in which the Sb is chelated by a [CfNPr ls] dianion and a [Pr NHC(NPr )2] monoanion (Figure 16). Supramolecular... 

The synthesis, structures, and reactivity of neutral and cationic mono- and bis(guanidinato)zirconium(rV) complexes have been studied in detail. Either salt-metathesis using preformed lithium guanidinates or carbodiimide insertion of zirconium amides can be employed. Typical examples for these two main synthetic routes are illustrated in Schemes 73 and 74. Various cr-alkyl complexes and cationic species derived from these precursors have been prepared and structurally characterized. 

An unusual porphyrin-supported hafnium guanidinate was obtained from the reaction of (TTP)Hf=NAr (TTP = meso-tetra-p-tolylporphyrinato dianion, Ar = 2.6-diisopropylphenyl) with 1,3-diisopropylcarbodiimide. The molecular structure of the product, (TTP)Hf[Pr NC(NPr )(NAr)] is shown in Figure 24. ° ... 

Iridium chemistry also holds a rare example of a monodentate guanidinate ligand. The monomeric parent amido complex Cp Ir(PMe3)(Ph)(NH2) cleanly undergoes an insertion reaction on treatment with diisopropylcarbodiimide (Scheme 153). Spectroscopic data and an X-ray structural analysis revealed the presence of a nonchelating guanidinate ligand. ... 

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