Penta-amines

The majority of penta-amine ligands studied are the compounds presented as 174-177 [285e] ... 

The topology of the complexes of these ligands is discussed extensively in a review [28 5e] and in a monograph [263]. In addition to the ligands described above, the aniline derivative may participate as tri-, tetra-, and penta-amine ligands, as for example 181 and 182 [285e] ... 

PNDA = p-dinitroso diphenyl amine PETA-penta erythritol triacrylate DHBP-peroxy hexane values in parentheses are after aging at 100°C, 72 h. 

DL-Valiolamine (205) was synthesized from the exo-alkene (247) derived from 51 with silver fluoride in pyridine. Compound 247 was treated with a peroxy acid, to give a single spiro epoxide (248, 89%) which was cleaved by way of anchimeric reaction in the presence of acetate ion to give, after acetylation, the tetraacetate 249. The bromo group was directly displaced with azide ion, the product was hydrogenated, and the amine acety-lated, to give the penta-A, 0-acetyl derivative (250,50%). On the other hand. 

The monocation tris(diethylether) ethylzinc is formed from diethyl zinc as a tetrakis(penta-fluorophenyl)borate salt.85 Longer-chain linear and cyclic ether complexes (2) of zinc alkyls have also been observed. The reaction between zinc dialkyls and primary amines gives a number of structurally diverse products dependent on the reaction conditions and the amine.86 The... 

Severin and coworkers reported (146) the reaction of tris(2-aminoethyl)amine and 4-formylphenylboronic acid with penta-erythritol to give, via multicomponent assembly, the boronic acid based macrobicyclic cage 35 (Fig. 25). The cage has the form of an ellipsoid with a diameter of 20.5 A and binds two Cud) ions in a fashion similar to the smaller tren-based cryptands. The reversible formation of boronic esters has also been employed to build other hollow structures such as nanotubes (147) and porous covalent organic frameworks (148,149). 

Main routes to 71-donor-substituted allenylidene complexes include (1) the nucleophilic addition of secondary amines to Fischer-type carbenes [M =C(OR ) C=CR (C0)5] (M = Cr, W) [9], (2) the Lewis-acid induced abstraction of NR2 groups from anionic complexes [M C=CC(NMe2)3](CO)5] (M = Cr, W) [9], and (3) the regioselective addition of protic nucleophiles to metallacumulenylidenes with more extended unsaturated carbon chains, such as butatrienylidenes or penta-tetraenylidenes [10]. In the following sections updated syntheses are presented by Periodic Group. 

Oxidation of 2-acetyldibenzothiophene with selenium dioxide in dioxane gave 2-dibenzothiopheneglyoxylaldehyde (129) (27%, penta-hydrate), which condensed with 2 moles of p-aminobenzoic acid to yield the corresponding aminal. Both compounds possessed antiviral activity. 

Ni" forms square-planar bis-complexes with the amidate anions of L-Val, L-Phe, and L-Pro. The structure of bis(Gly)-bis(imidazole)nickel(ii) has been reported and the configuration around the metal atom is cis-O(carboxyl), cis-N(amine), cis-N(imidazole). Tetra- and penta-peptide complexes of nickel(ii) consume oxygen in neutral solutions as the metal ion catalyses peptide oxidation to give a number of products, including amides of amino-acids and peptides, oxo-acids, and C02- ... 

The synthesis of valsartan (2) by Novartis/Ciba-Geigy chemists is highlighted in Scheme 9.5. Biphenylbenzyl bromide 18 is converted to biphenyl acetate 19 in the presence of sodium acetate in acetic acid. Hydrolysis of 19 followed by Swern oxidation delivered the biphenyl aldehyde 20, which underwent reductive amination with (L)-valine methyl ester (21) to give biphenyl amino acid 22. Acylation of 22 with penta-noyl chloride (23) afforded biphenyl nitrile 24, which is reacted with tributyltin azide to form the tetrazole followed by ester hydrolysis and acidihcation to provide valsartan (2). [See Biihlmayer et al. (1994, 1995).]... 

Occasionally, a per-O-acetylated amine can be used in the synthesis of a partially acetylated compound. For example, 2-amino-2-deoxy-neo-inositol pentaacetate, which was prepared from hygromycin A, was converted by deamination into 1,2,3,4,6-penta-O-acetyl-myo-inositol.226... 

Table 42 Complexes with Tri-, Tetra- and Penta-dentate Amines...

Formation of the imine and subsequent reduction can often be achieved in one pot . Thus, a microwave-assisted reductive amination-cyclisation domino reaction was used as the key step in the synthesis of perhydrocyclo-penta[ij]quinolizines from 1,5,9-triketones. This type of heterocycle is an important structural element in a series of alkaloids. The reaction of the triketone with ammonium formate in PEG-200 was performed within 1 min using microwave irradiation of370 W in a domestic microwave oven. Amixture oftwo ofthree possible stereoisomers was obtained in 87% overall yield (Scheme 4.29)52. 

In contrast to aliphatic amines, aromatic amines hardly react with C02 [21a] because of their poorer basicity. However, in the presence of suitable auxiliary bases (B) (such as amidines or penta-alkylguanidine superbases), carbamate salts (BH)02CNRAr (R = H, alkyl) can be generated in solution, as supported by spectroscopic and reactivity data [29]. It has been shown that even tributylamine may be effective if a suitable alkali metal salt is also present in solution in the latter case, the N-arylcarbamate has been isolated as an alkali salt (Equation 6.3)... 

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