Aliphatic amines, chelating

The use of an extended arene (tetrahydroanthracene) in [OsCl(en)(ri6-tha)]+ (29) gave rise to a similar potency (112). This is in contrast with the data for ruthenium-arenes, where the same substitution gave rise to a 10-fold increase in activity. Further work therefore needs to determine if the extended Os-arenes can intercalate into DNA in a manner similar to Ru-arenes. Replacement of the iV /V-chelating ligand en for other AyV-bidentates with pyridine, aliphatic amine, or azopyridine donor atoms leads to loss of activity, probably because of slower hydrolysis and higher acidity of the coordinated water (112). 

The aliphatic alkyleneamines are strong bases exhibiting behavior typical or simple aliphatic amines. Additionally, dependent on the location of the primary or secondary amino groups in the alkyleneamines. ring foimatiun with various reactants can occur. This same feature allows for metal ion complcxation ur chelation. The alkyleneamines are somewhat weaker bases than aliphatic amines and much stronger bases than ammonia as the pK , values indicate... 

Acetonitrile and benzonitrile, aliphatic amines, pyridine, amides (especially DMF), alcohols, and propylene-carbonate are used as solvents in the syntheses of this type. All of them have properties of ligands. Moreover, such classic N-donors as 2,2 -bipy and 1,10-phen were used as ligands, as well as compounds with P-(triphenylphosphine) and O- donor centers (urea, pyridine-N-oxide, triphenyl-phosphinoxide) and chelating ligand systems ((3-diketones, 8-hydroxyquinoline, dimethylglioxime) [202]. 

Recently, Sames and co-workers showed an interesting application, in which it was demonstrated that the Shilov chemistry permits heteroatom-directed functionalization of polyfunctional molecules [16]. The amino acid valine (10) was allowed to react in an aqueous solution of the oxidation catalyst PtCU and Cu(ii) chloride as stoichiometric oxidant (Scheme 3). At temperatures >130 °C a catalytic reaction was observed, and a regioselective C-H functionalization delivered the hydroxyvaline lactone 11 as a 3 1 mixture of anti/syn isomers. It was noted that the hydroxylation of amino acid substrates occurred with a regioselectivity different from those for simple aliphatic amines and carboxylic acids. The authors therefore proposed that the amino acid functionalization proceeded through a chelate-directed C-H activation. 

For the latter CNS receptor ligands, different types of chelators have been introduced to the basic receptor binding framework. Originally a bidentate Schiff base was introduced by the reaction of an aliphatic amine with pyridine-aldehyde. Labelling occurred at low concentration and the radio conjugate was physiologically stable. Although receptor affinity was fully retained, brain uptake was low [67]. ACp was introduced at the same position and, as described earlier, and receptor affinity was perfectly retained. No brain uptake data are... 

Wald J, Alberto R, Ortner K, Candreia L (2001) Aqueous one-pot synthesis of derivatized cyclo-pentadienyl-tricarbonyl complexes of Tc-99m with an in situ CO source application to a serotonergic receptor ligand. Angew Chem Int Edit 40 3062-3066 Wei LFi, Babich J, Zubieta J (2005) Bifunctional chelates with mixed aromatic and aliphatic amine donors for labeling of biomolecules with the [Tc(CO)3] and [Re(CO)3] -cores. Inorg Chim Acta 358 3691-3700... 

Chelating ferrocene phosphine L18 was reported by Hartwig to efficiently catalyze the amination of most aryl chlorides with any type of primary aliphatic amine, imine, or hydrazine at 80-100 °C with NaOf-Bu in DME. Base sensitive aryl chlorides, or those containing acidic protons, may be aminated using LiHMDS as the stoichiometric base. Impressively, catalyst loadings as low as 0.005 mol% can be used. 

In 2005, Trauthwein s group reported the synthesis of an easy-to-handle and stable racemisation catalyst for secondary alcohols by an in situ mixture of readily available [Ru(p-cymene)Cl2]2 with chelating aliphatic amines. Optimisation of the reaction revealed that A7,A7,A7 A7 -tetramethyl-l,3-propanedia-mine as the ligand racemised aromatic alcohols completely within five hours. The combination of this catalyst with lipase CAL-B showed a good performance for the DKR of various alcohols in the presence of p-chlorophenyl acetate as the acyl donor, as shown in Scheme 4.14. 

---