Synthesis of ι-(bromomethyl)bipyridines and related ι-(bromomethyl)pyridinoheteroaromatics: useful functional tools for ligands in host molecules
摘要:
Pyridines and 2,2'-bipyridines have been employed as useful ligands in molecular recognition chemistries. Halomethyl-substituted bipyridine or oligopyridine derivatives were required for the assembly of bipyridine or oligopyridine units with a supporting mother functional part in artificial biofunctional molecules. A series of omega-(bromomethyl)bipyridines and related omega-(bromomethyl)pyridinoheteroaromatic compounds (types I-III) were synthesized in this paper. Preparation of oligopyridines and pyridinoheteroaromatic compounds have been carried out by either intermolecular ligand coupling of alkyl heteroaryl sulfoxide with pyridyllithium or intramolecular ligand coupling of pyridyl heteroaryl sulfoxide with methylmagnesium bromide for the type I compounds. The type II and III compounds were synthesized by addition of pyridyllithium to pyridinecarboxaldehyde. The omega-bromo group was introduced by radical bromination reaction of methylpyridyl group using NBS and BPO (dibenzoyl peroxide) or bromination of omega-(hydroxymethyl)pyridine using a combination of CBr4 and Ph3P.
A kinetic resolution of racemic pyridyl and bipyridylethanols was performed by Candida antarctica lipase with vinyl acetate in diisopropyl ether, in which (R)-alcohol was acetylated stereoselectively, and both the acetate 2 and the remaining (S)-alcohol 1 were obtained with high enantiomeric excesses. (S0-Oligopyridylethanols, 7 and 8 were prepared by a coupling reaction of (S)-1b and (S)-1e with ethyl