Design, Synthesis And Application Of Bipyridine Derivatives And Their Transition Metal Complexes

A series of new type of bipyridine ligands have been designed and synthesized, including cation-tagged, polyethylene glycol ether-based and anion-tagged 2,2'-bipyridines. The cationic 2,2'-bipyridines were prepared from 4,4'-bis(bromomethyl)-2,2'-bipyridine by N-alkylation method in 35%-98% yields; polyethylene glycol ether-based 2,2'-bipyridine was synthesized by nucleophilic substitution reaction in 65% yield; and sodium 2,2'-bipyridine-4,4'-diyldimethanesulfonate was prepared from 4,4'-bis(bromomethyl)-2,2'-bipyridine and sodium sulfite. The structures of these functionalized bipyridine ligands were analyzed by NMR and HR-MS(ESI).Oxidization of primary alcohols to the corresponding aldehydes was effected in yields 53%-94% within 12 hours at 65℃by using in situ generated functionalised 2,2'-bipyridine copper complexes from CuCl in ionic liquids. The copper complex supported by polyethylene glycol ether-based 2,2'-bipyridine turned out to be the most active oxidation catalysts giving products in almost quantitative yield. And the catalyst system could be reused for 3 times with little loss activity.During our investigation of the application of 2,2'-bipyridine-silver complexes in A3-reaction of aldehydes, amines and alkynes, the cationic 2,2'-bipyridine cotianing N-cyclohexyl-N'- arylmethelene imidazolium bromide showed the highest catalytic activity. Prompted by the result, structurally well-defined N-heterocyclic carbene silver chlorides and bromides supported by N-cyclohexyl-N'- arylmethelene imidazolylidene were synthesized by reaction of the corresponding imidazolium halides with silver(I) oxide. The monomeric complexes (CyNaph-NHC)AgX showed higher catalytic activity than the dimeric [(CyBn-NHC)AgX]2 as well as the cationic biscarbene silver nitrate in the model three component reaction of 3-phenylpropionaldehyde, phenylacetylene and piperidine, with (CyNaph-NHC)AgCl performing best and giving product in almost quantitative yield within 2 hours at 100℃. Alkyl alkynes, such as octyne, and aromatic aldehydes, both electron-rich and deficient, also reacted under similar conditions.