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Stereoselective Synthesis of α,β‐ trans 1‐Spiro‐β1‐lactones by Diels‐Alder Cycloaddition of 1,3‐Dienes to α1‐Methylene‐β1‐lactone and Their Decarboxylation by Pyrolysis to ( E )1‐Alkylidenecycloalkenes, a Convenient Olefination Method
Author(s) -
Adam Walder,
Salgado Victor Oswaldo Nava,
Peters EvaMaria,
Peters Karl,
Schnering Hans Georg Von
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260632
Subject(s) - chemistry , stereoselectivity , cycloaddition , decarboxylation , isomerization , isopropyl , lactone , methylene , diels–alder reaction , stereochemistry , medicinal chemistry , organic chemistry , catalysis
A number of spiro‐β1‐lactones was prepared in good to excellent yields through stereoselective [4 + 2] cycloaddition of β1‐isopropyl‐α1‐methylene‐β1‐lactone ( 1 ) with acyclic, cyclic, heterocyclic and aromatic 1,3‐dienes by sealed‐tube reaction at moderate temperatures (50 – 130°C). Flash pyrolysis of the resulting spiro‐β1‐lactones 2 in the gas phase at 400°C afforded by decarboxylation exclusively the corresponding ( E )1‐isopropylidenealkenes in high yields with retention of the initial geometry and without double bond isomerization. This olefination method constitutes an excellent stereoselective synthesis of ( E )1‐alkylidenecycloalkenes.