1,5-Hydrogen shift and other isomerization reactions of certain ethyl octadecatrienoates

1,5-Hydrogen shift and other isomerization reactions of certain ethyl octadecatrienoates

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,...

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Bibliographic Details
Published in:Tetrahedron Vol. 53; no. 12; pp. 4531 - 4538
Main Authors: Matikainen, Jorma, Kaltia, Seppo, Hämäläinen, Markku, Hase, Tapio
Format: Journal Article
Language:English
Published: Elsevier Ltd 24-03-1997
Online Access:Get full text
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Summary: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. Graphic
ISSN:0040-4020
1464-5416
DOI:10.1016/S0040-4020(97)00127-0