81199-02-2Relevant academic research and scientific papers
Reactions retrodieniques. XII. Cycloreversions et rearrangements d'ethano-9,10 dihydro-9-10 anthracenes cyclopropaniques
Lasne, Marie-Claire,Ripoll, Jean-Louis
, p. 340 - 344 (2007/10/02)
Five Diels-Alder adducts of anthracene, containing respectively the spiro cyclopropane (3), vinylcyclopropane (4), allenylcyclopropane (5) and methylenecyclopropane systems (6 and 7) have been synthesized and their flash thermolytic behaviour investigated.Whereas the adduct 3 undergoes exclusively a retro-Diels-Alder cleavage leading to methylenecyclopropane, two types of rearrangements are observed, owing to their structure, as predominant reaction paths with compound 4-7 : the adducts 4 and 5, possessing a vinylcyclopropane unit, almost only rearrange into the corresponding cyclopentene 14 and methylenecyclopentene 15, respectively; on the other hand, the methylenecyclopropene adducts 6 and 7 undergo a more unexpected rearrangement of the anthracenic framework leading to the polycyclic methylenecyclobutanes 19 and 20.The structure proposed for 19 follows unambiguously from its spectral properties and is confirmed by its ozonolysis yielding the cyclobutanone 21.In the same way, the retro-Diels-Alder cleavage of the adducts 4-7, also observed as a minor reaction path (10-40percent), is followed by the isomerization of the firstly obtained cyclopropanic cumulenes, leading to 1,4-hexadiyne (from 5), dimethylenecyclopropane (from 6), or 1-hexen-4-yne and ethylidenemethylenecyclopropane (from 7).
