Substituted Dipyridylethenes and -ethynes and Key Pyridine Building Blocks

Authors:
  • PWPaul-Michael Windscheif
    Paul-Michael Windscheif
  • FVFritz Vögtle
    Fritz Vögtle
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Abstract
Various new 2,5-disubstituted pyridines were prepared. The 2-substituted 5-formylpyridines 8, 15a-b were obtained by reduction of the nicotinic acid 3, hydrolysis of the bis(morpholino)methylpyridine 6 or the reaction of 5-bromopyridines 12 and 14 with lithium butoxide in DMF. Dipyridylethenes 16a-b,e were synthesized by Wadsworth-Emmons reaction with pyridyl phosphonate 7 or by coupling of the aldehydes by McMurry reaction to the ethenes 16c-d. After bromination of the C=C double bond of the dipyridylethenes 16a-d, dipyridylacetylenes 18a-d were obtained via elimination of the 1,2-dipyridyl-1,2-dibromoethanes 17a-d.