1 4P6 (3e)-3-(thiophen-2-ylmethylidene)-3,4,5,6-tetrahydro-2,3'-bipyridine 1.000 2 4P7 (3e)-3-(1h-pyrrol-3-ylmethylidene)-3,4,5,6-tetrahydro-2,3'-bipyridine 0.800 3 ZY5 4-[(E)-5,6-dihydro-2,3'-bipyridin-3(4h)-ylidenemethyl]-3-methoxyphenol 0.739 4 ZY7 (3e)-3-[(2,4-dimethoxyphenyl)methylidene]-3,4,5,6-tetrahydro-2,3'-bipyridine 0.708