Abstract
Benzylidene products resulting from acid-catalyzed aldol condensations of aryl aldehydes and anabaseine at position 3 of the tetrahydropyridine ring have E stereochemistry. In spite of a chemical shift scale ranging only over 0.11 ppm the methylene protons (H-6) adjacent to the imino group of the tetrahydropyridine ring show an excellent Hammett correlation using σM and σP values. Methoxy and chloro groups in an ortho position require a σ1, parameter. Substrates with one or two ortho methyl groups deviate. AM1 and MM2 calculations indicate that both the phenyl and pyridyl rings are twisted out of a common plane defined by the central ring.
Original language | English |
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Pages (from-to) | 171-180 |
Number of pages | 10 |
Journal | Heterocycles |
Volume | 35 |
Issue number | 1 |
DOIs | |
State | Published - 1 Jan 1993 |