Pyridine Framework Research Articles

Enantiospecific Synthesis of Annulated Nicotine Analogues from d- and l-Glutamic Acid. Pyridotropanes

The conformationally restricted nicotinoid 1-methyl-8-azabicyclo[3.2.1]octano[2,3-c]pyridine, pyrido[3,4-b]tropane, has been prepared enantiospecifically from both d- and l-glutamic acid. The method involved coupling of pyroglutamic acid derivatives with ortho-lithiated 4-chloropyridine, followed by intramolecular imine formation and reduction to generate the d- and l-5-substituted proline esters. Chloro-iodo exchange and side chain extension gave the precursor for the [3.2.1] system. Construction of the 8-azabicyclo[3.2.1]octano-[2,3-c]pyridine framework was achieved by an intramolecular Heck reaction. Subsequent ozonolysis gave the ketone which was reduced to the carbinol or methylene, yielding the fused nicotine analogues.

Enantioselective cyclopropanation of styrene with optically active nitrogen ligands based on the pyridine framework

Copper (I) complexes prepared in situ from copper(I)-triflate and 8 optically active pyridine ligands, mainly 2,2′-bipyridines and 2,2′:6′,2′-terpyridines were used as chiral catalysts for the enantioselective cyclopropanation of styrene by ethyl diazoacetate. ee up to 32% was obtained.