Amidine group

During these structural studies by chemical methods, we found the following interesting reactions, which were substantially useful for the presence of an unique amidine group. 

The charges of the molecule are important for binding. When the amidine group accepts a proton and becomes an amidinium ion, noformycin and amidinomycin become biscationic and bind strongly to AT sequences. These two molecules have large pKa values at both basic sites and, as such, are biscationic at physiological pH. 

The amidine group reacted more easily than the aromatic amino group with EMME in boiling ethanol besides the condensation, ring closure usually takes place to give pyrimidinecarboxylate in good yield (e.g., 80EUP15772) (Scheme 11). 

The involvement of an amidine group as C-N partner for interchange with the C(2)-N part of the pyridine ring has been observed during base treatment of the 3-formamidopyridinium salt 2-amino-3-formylpyridine is formed in a reasonable yield (Scheme IV.50) [79ZN(B)1019].The reaction follows the same pathway as described in Scheme IV.49. 

Amidines are formed in hydrolytic polymerizations of lactams but do not limit the polymer molecular weight. Molecular weight buildup is not impeded since the carboxyl end groups of growing polymer are quite reactive toward amidine groups [Bertalan et al., 1984]. 

The observation that activity is retained when the guanidine is replaced by an amidine group points to the considerable degree of freedom that exists in this series for receptor recognition. This also applies for the rest of the chain since naturally occurring amino acids can be replaced by other groups. The resulting compounds should also be less likely to be metabolized by proteolytic enzymes... 

Sulfide groups attached to other carbon functionalities, e. g. the cyano and amidine groups in 16 and 17, respectively, are oxidized to the sulfonic acid or sulfonyl chloride with cleavage of the S — C bond.J02-303... 

The kinetics and mechanism of the phosphorus-catalysed dimerization of acrylonitrile to give 1,4-dicyanobut-l-ene and 2,4-dicyanobut-l-ene have been studied.114 The reactions of aryhminodimagnesium (138) with //-substituted p-cyanobenzophenones, l-cyano-9-fluorenenone, o-, m-, and p-dicyanobcnzcnes, and o-, m-, and p-nitrobenzonitriles have been examined.115 The effect of pressure on the reaction of 3 -methyl- l-(4-tolyl)triazene (139) and benzoic acid in chloroform and acetonitrile has been studied.116 The effect of acids on the rate of urethane formation from alcohols and isocyanates in the presence of alkyltin carboxylates has been examined.117 A Hammett a value has been reported for the amidine group N=CHNMe2 and used for the prediction of the basicity of sites in bifunctional amidines.118... 

Fig. 5 Complexes formed (a) between amidine groups in the functional monomer V,lV -diethyl-4-vinyl-benzamidine and carboxyl groups in the imprinting template IV-terephthaloyl-D-phenylglycine [82] and (b) between amidine groups in the imprinting template pentamidine and carboxyl groups in the functional monomer methacrylic acid [83]...

In a similar study, Hwang et al. [141] studied the effect of spacing between the amidine groups on pDNA binding ability and gene expression by systematic modifications to the number of methylene groups (from 4 to 10) in between the amidine units (Fig. 20). The polymers (fi-CDPs) contained four to five repeat units and compacted pDNA into nanoparticles of 12-150 nm in diameter. This study also... 

Arretz, E., Lopez, F. Method for preparing organic disulfides and polysulfides from mercaptans and sulfur in the presence of heterogeneous styrene-divinylbenzene copolymer catalysts having pendant guanidine or amidine groups. 1996, WO 9721673. 

The coexistence of amino and formamide groups along the polymer backbone may form amidine groups (Scheme 2). 

Scheme 2 Functional groups in a Lupamine polymer with a low number of hydrolysed formamide groups. An amino and formamide group formed an amidine group...

---