Guanidines, alkyl

T2 resin synthesis of substituted amines, amides(peptides), (thio)urcas, hydrazines, alcohols, esters guanidines alkyl halides, sulfoximines. ... 

Although in the dry state carbon tetrachloride may be stored indefinitely in contact with some metal surfaces, its decomposition upon contact with water or on heating in air makes it desirable, if not always necessary, to add a smaH quantity of stabHizer to the commercial product. A number of compounds have been claimed to be effective stabHizers for carbon tetrachloride, eg, alkyl cyanamides such as diethyl cyanamide (39), 0.34—1% diphenylamine (40), ethyl acetate to protect copper (41), up to 1% ethyl cyanide (42), fatty acid derivatives to protect aluminum (43), hexamethylenetetramine (44), resins and amines (45), thiocarbamide (46), and a ureide, ie, guanidine (47). 

Amidines and related systems such as guanidines react with a-halogenoketones to form imidazoles. a-Hydroxyketones also take part in this reaction to form imidazoles, and a variety of substituents can be introduced into the imidazole nucleus by these procedures. Reaction of the a-halogenoketone (73) with an alkyl- or aryl-substituted carboxamidine (76) readily gave the imidazole (77) (01CB637, 48JCS1960). Variation of the reaction components that successfully take part in this reaction process is described in Chapter 4.08. 

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). ... 

An early application of this reaction to the preparation of barbiturates starts by the condensation of the ketone, I21, with ethyl cyanoacetate by Knoevenagel condensation. Alkylation of the product (122) with ethyl bromide by means of sodium ethoxide affords 123. Condensation of this intermediate with guanidine in the presence of sodium ethoxide gives the diimino analog of a barbiturate (124). Hydrolysis affords vinbarbital (111). > ... 

In a somewhat similar vein, alkylation of the urea derivative 109 with methyl iodide affords the S-methyl ether 110. Condensation of that with taurine (111), leads to the guanidine 112, again by an addition elimination process. The product is the anthelmintic agent netobimin (112) [271. 

Rolgamidine (14) is a dihydropyrrole derivative which has antidiarrheal activity It can be synthesized by alkylation of trans 2,5-dimethyl-3 pyrroline (12) with methyl bromoacefate to give 13 An amide-ester exchange reaction with guanidine hydrochloride completes the synthesis of rolgamidine (14) [3]... 

Acyl-Guanidine werden durch Lithiumalanat zu Alkyl-guanidinen reduziert (s.S. 

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). 

Metathetical routes using bulky lithium guanidinates as starting materials have also been employed to synthesize bis(guanidinato) lanthanide halides as well as reactive alkyls and hydrides. Scheme 63 shows as a typical example the formation of the lutetium chloro precursor, which was isolated in 76% yield. ... 

Homoleptic lanthanide(III) tris(amidinates) and guanidinates are among the longest known lanthanide complexes containing these chelating ligands. In this area the carbodiimide insertion route is usually not applicable, as simple, well-defined lanthanide tris(alkyls) and tris(dialkylamides) are not readily available. A notable exception is the formation of homoleptic lanthanide guanidinates from... 

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. 

The guanidinate-supported titanium imido complex [Me2NC(NPr02l2Ti = NAr (Ar = 2,6-Me2C6H3) (cf. Section IILB.2) was reported to be an effective catalyst for the hydroamination of alkynes. The catalytic activity of bulky amidinato bis(alkyl) complexes of scandium and yttrium (cf. Section III.B.l) in the intramolecular hydroamination/cyclization of 2,2-dimethyl-4-pentenylamine has been investigated and compared to the activity of the corresponding cationic mono(alkyl) derivatives. 

An alternative to the Gabriel synthesis, in which alkyl halides can be converted to primary amines in good yields, involves treatment of the halide with the strong base guanidine followed by alkaline hydrolysis. There are several alternative... 

Diamines can also react with only one equivalent of isothiocyanate to form bi-functionnal amine-thiourea ligands 59-68% yields obtained for several alkyl isothiocyanates. However, reaction of phenyhsocyanate with 1,2-diamines could also lead to the formation of the guanidine derivative by cyclisation and elimination of H2S (Scheme 4) [42,43]. 

As yet, a number of experiments have failed to convert ureas 205 such as N-phenylurea or imidazolin-2-one by silylation amination with excess amines R3NHR4 such as benzylamine or morpholine and excess HMDS 2 as well as equivalent amounts of NH4X (for X=C1, I) via the silylated intermediates 206 and 207 in one reaction step at 110-150°C into their corresponding guanidines 208 with formation of NH3 and HMDSO 7 [35] (Scheme 4.13). This failure is possibly due to the steric repulsion of the two neighbouring bulky trimethylsilyl groups in the assumed activated intermediate 207, which prevents the formation of 207 in the equilibrium with 206. Thus the two step Rathke-method, which demands the prior S-alkylation of 2-thioureas followed by amination with liberation of alkyl-mercaptans, will remain one of the standard syntheses of guanidines [21, 35a,b,c]. 

The feasibility of identifying these edges of water base pairs has been supported by our studies of mitomycin C interacting with the model system for AT base pairs 29). Interactions of either component with mitomycin C are not observed but a complex is formed when all three components are present. Chemical shift changes observed in the NMR spectra support the structure 47 for the termolecular complex. The broader implication is that mitomycin C will likewise recognize the minor groove side of a G-C pair (it is known to alkylate the guanidine on this side)31 ... 

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