Amidinium salts tertiary

The selectivity of acylations or alkylations of polyamines can also be modulated by protonation [78] or by conversion to cyclic aminals [71, 79, 80]. The latter strategy has, for instance, been used successfully for the preparation of monofunctionalized 1,4,7-triazacyclononanes (Scheme 10.18). In this reaction the first alkylation leads to the formation of an amidinium salt, which is more difficult to alkylate than a tertiary amine. Thus, the use of only one equivalent of alkylating agent leads to a clean monoalkylation. 

It should be noted that Jochims and coworkers first carried out the reaction starting from carboxamides139,140. Until recently almost no acylated persubstituted amidinium salts 306 were obtained by reaction of nitrilium salts with tertiary carboxamides 305 (equation 84). Starting from secondary carboxamides 307, mixtures of A1-acylated A A -disubstituted amidinium salts 308 and 309 are isolated (equation 85). Primary carboxamides 310 undergo dehydration by the nitrilium hexachloroantimonates 290 to... 

Sulfonyl halides (e.g. benzenesulfonyl chloride) form adducts (11) with acid amides in an equilibrium reaction. From these adducts or via adducts of this type 0-sulfonated lactim ethers, isonitriles, adenine, nitriles, amidines, amidinium salts and formic acid esters were prepared. The adducts from DMF and chlorosulfonamides (12) can be used to prepare amidines or amidrazones. A/-Chlorosulfonylcarboxylic acid amides yield nitriles on treatment with DMF or other tertiary amides, presumably via an acid amide sulfonyl chloride complex (13 equation 3). ... 

Many vinylogous amidinium salts, e.g. (185) and (186) (Scheme 25), are readily available by double formylation of CHa-acidic or alkenic compounds. Reviews on the chemistry of vinylogous amidinium salts are available. The first azavinylogous foimamidinium salt (187 Scheme 26) was prepared in 1960 by reaction of DMF with cyanuric chloride. The mechanism of this reaction has been estab-lished. Based on these findings new methods for the synthesis of these compounds were developed, e.g. the reaction of isocyanatomethyleneiminium salts with tertiary formamides affords salts (187). In the synthesis of the salts (187) cyanuric chloride can be replaced by phosphorus nitride chloride (PNCl2)3. ... 

Adducts from tertiary amides (mostly DMF) or lactams with POCI3 or PCI3 were reacted with different kinds of primary amines and amine derivatives to give amidinium salts which were deprotonated to pro-... 

It is well known that halomethyleneiminium salts, often prepared in situ (see Section 2.1.2.2) react with ammonium salts, primary amines, secondary amides, urea and IV-substituted ureas to afrbrd amidinium salts, from which the free amidines can be obtained by addition of bases. > 4 Some recent results are given below. Dimethylformamide chloride and other 7V,iV-disubstituted formamide chlorides were reacted with acetanilides, chloroacetanilides, 6-aminopenam derivatives, 2-aminopyrimidine, 4-aminouracil, 2-amino-4-chloropyridazine, 2-aminothiazole, 2-aminobenzothiazole and thiobenzamides to give the amidines via the amidinium salts. In the reaction of MA -disubstituted formamide chlorides with thiobenzamides the solvent seems to be decisive for the course of the reaction. In tertiary formamides the thiobenzamides are desulfurized to nitriles, whereas in CHCI3 or CCI4 amidinium salts (296 Scheme 45) are formed. From trimethylsilyl isocyanate and the fluorinated amine (297) the /V-fluorocarbonylamidine (298) is accessible. ... 

Amidinium salts (obtainable by various methods, compare Section 2.1.2.5) which are not peralkylated at nitrogen are converted to amidines by treatment with strong bases, e.g. aqueous alkali metal hydroxides, alcoholic alkoxides, tertiary amines etc. As already mentioned it is not difficult to alkylate amidines (see Section 2.7.2.5.4), thus by subsequent alkylation and deprotonation reactions amidines can be synthesized carrying the desired substituents at nitrogen, e.g. (308 Scheme 47). A series of trisubstituted formamidines have been prepared by reaction of anilines with the azavinylogous form-amidinium salt (309). ... 

The stability of 1,1-enediamines and their amidinium salts merits comment. Secondary and tertiary 1,1-enediamines substituted by two )S-electron-withdrawing substituents such as 104 are quite stable, being unaffected by refluxing with aqueous sodium hydroxide. Treatment of their salts with base regenerates the parent enediamines. On the other hand, 103 or its salt 106, undergoes hydrolysis to give iV-pentamethylene-TV -phenylmalonamide. Simple 1,1-enediamines or their salts are very sensitive to hydrolysis, leading to amides... 

Gompper and Kohl have reported an intramolecular reaction of tertiary ene-diamines bearing a keto group. Treatment of amidinium salt 164a with ethyldiisopropy-lamine in acetone results in the formation of the pyrrolopiperidine derivative 166 in 79% yield. Interestingly, reaction of 164b with sodium hydride in tetrahydrofuran very rapidly forms the pyrrolidinimine 167 in 91% yield (equation 62) (see Chapter 16). 

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