178413-47-3Relevant academic research and scientific papers
A versatile domino synthesis affording novel S- and U-shaped terpyridines. Synthesis, properties and crystal structure
Keuper, Ralf,Risch, Nikolaus,Floerke, Ulrich,Haupt, Hans-Juergen
, p. 705 - 715 (2007/10/03)
The development of a simple and general method for the preparation of multifunctional terpyridines is described. The treatment of the ketones 1a-g with ternary iminium salts results in the formation of the isomeric terpyridines 6 and 8 (according to a domino reaction). A possible reaction mechanism is discussed. In some cases the isolation of the postulated dihydropyridine intermediates was successful. The isolation of the 1,4-dihydropyridines 5e, 5j, and 5r (donor-substituted) is surprising, because most of the stable dihydropyridines are acceptor-substituted. In several cases the yields of such domino reactions are very high (>80%). Whether S-or U-shaped terpyridines are formed is immediately recognized by NMR spectroscopy. Some special cases (8c, 8e, 6h) were investigated by means of single-crystal X-ray analysis. VCH Verlagsgesellschaft mbH, 1996.
