N. Kanomata, Shinsuke Yamada, Takayuki Ohhama
Apr 24, 2006
Citations
0
Influential Citations
11
Citations
Journal
Tetrahedron
Abstract
Abstract Synthesis of various bridged nicotinates 6 having [n](2,5)pyridinophane skeletons (n=8–14) was accomplished by the unique pyridine-formation reaction of methyl propiolate with a series of formyl-substituted (vinylimino)phosphoranes 5 , which were prepared from the corresponding cycloalkanones 1 via Vilsmeier–Haack formylation giving chloro-substituted cycloalkenals 2 , their thermal and photochemical transformation to formyl azirines 4 , and the following ring-opening reactions with triphenylphosphine. The HPLC analysis of [11](2,5)pyridinophane derivatives, (Sp,S)-14 and (Rp,S)-14 , showed that these diastereomers rapidly epimerize themselves at room temperature and that their planar-chirality was thermodynamically less stable as compared to the corresponding [11](2,5)cyclophane systems.