Diamino compounds acylation

One of the most common approaches to benzimidazole synthesis (but less contunon for uncondensed imidazoles) utilizes an arylene (or alkylene) 1,2-diamino compound in which one of the amino functions has been acylated or thioacylated. The starting material has to be functionalized in such a... 

Eight-membered heterocycles are prepared by the common strategy of a [7 -(-1) cyclization of a diol or diamino acyclic precursor with a one-carbon fragment such as phosgene, dihalomethane or formaldehyde (Schemes 20, 21 and 23 and Equations (9)-(12)). Other dihaloalkanes have been employed in cyclizations either with diamino compounds activated by tosylation (Scheme 26 and Equation (18)) or acylation (Equation (15)), or with dithiols (Equation (17)). 

The conversion of biguanides into guanamines under the influence of acylating agents is well known (see also Section VII 12). Acetic anhydride or benzoyl chloride in conjunction with alkali react with the parent compound, gelding 2-methyl- 519) or 2-phenyl-4,6-diamino-s-triazine 17) (LXXXI R = Me or Ph) respectively. 

The last-mentioned application was the aim of a patent206 dating from 1971. 4,8-Diamino-2,6-dioxabicyclo[3.3.0]octanes, endo-endo as well as endo-exo isomers, were used as starting materials for polyamides. First, the diamines 129 were transformed into their salts with various dicarboxylic acids, and these were polymerized to compounds 130 containing acylated amino moieties as monomeric building blocks (see Scheme 30). 

The observation has been made that the l,2,5-thiadiazole-l,l-dioxide nucleus behaves like a strong acyl function and that the dichloro (76), dimethoxy (77), and diamino (75) derivatives are in fact an acid chloride, ester, and amide of a strong acid. The dichloro (76) compound is highly reactive toward nucleophiles and must be... 

The foregoing acids are crystalline solids, and in some cases may be crystallised from water. 5-Amino-2 4-dihydroxy-, 3 5-diamino-2-hydroxy-, and 4 5-diamino - 2 - hydroxyphenylarsinic acids reduce ammoniacal silver nitrate solution, the reaction being instantaneous with the latter two acids. 4-Acetylamino-8-hydroxy-2-nitrophenylarsinic acid, boiled with 2N sulphuric acid, yields 2 6-nitroaininophenol, but with potassium hydroxide the acetyl group is merely hydrolysed reduction of the acid with ferrous chloride produces the corresponding diamine. 3-Amino-4-hydroxyphenylarsinic acid tends to oxidise when recrystaUised from water, and when a cooled solution of the acid in 5 per cent, sodium hydroxide solution is treated with carbonyl chloride, it gives 1 2-dihydrobenzoxazolone-4-arsinic acid. 8-Amino-4-hydroxy-phenylarsinic acid also yields a number of N-acyl derivatives (see details on p. 296), the most important of which is the 8-acetylamino-compound,... 

The bishydrazones of DHA and related compounds have been studied and used to synthesize a number of nitrogen derivatives of DHA (18-23), Thus the bisphenylhydrazone of DHA is reduced by hydrogen/platinum to 2,3-diamino-2,3-dideoxyascorbic acid, which in turn can be converted to a variety of acyl derivatives. The structure of DHA phenylosazone is a hexenonelactone (24),... 

Verdini and coworkers [122] have introduced the 2-methyl-2-(2 -ni-tro)phenoxy-propionyl (Mnp) group for the preparation of stable monopro-tected gem-diamino alkyl residues 27 via IBTFA treatment of the carboxamide precursor 26. The precursor 26 is prepared by coupling amino a-carboxamide and 2-methyl-2-(2 -nitro)phenoxy-propionic acid as its O-succinimidyl ester 25. Hydrochloride salts, such as 27, are generally stable, crystalline compounds that can be stored at room temperature for several months. Once deprotonated, 27 is stable enough for acylation reactions (Scheme 9) [122]. 

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