J. Matikainen, S. Kaltia, M. Hämäläinen
Mar 24, 1997
Citations
0
Influential Citations
11
Citations
Journal
Tetrahedron
Abstract
Abstract Four new octadecatrienoic acid ethyl esters (4–7) were synthesized. On heating these undergo cyclization, via an intramolecular Diels-Alder (IMDA) reaction, mainly to stereoisomers of ethyl 4-(5-pentyl-1,2,3,3a,4,5,7a-hexahydroindenyl)-butanoate (CP-1, CP-2, CP-3, CP-4 and CP-5) and 3-(6-pentyl-1,2,3,4,4a,5,6,8a-octahydronaphthyl)propanoate. 1,5-Sigmatropic hydrogen shift reactions of the trienoic esters 4–7, all possessing a conjugated Z,E structure, precede the IMDA reactions. The 1,5-hydrogen shift reaction occurs in Z,E dienoic structures at a lower temperature than the Z,E to E,E isomerization.