887924-61-0Relevant articles and documents
Studies on thermal reactivity of β-(1,2-allenyl)butenolides and 2-allyl-3-allenylcyclohex-2-enones
Gu, Zhenhua,Ma, Shengming
supporting information; experimental part, p. 2453 - 2464 (2009/04/10)
A series of thermal pericyclic reactions of β-allenylfuranones have been studied. It was observed that β-allenylfuranones would undergo 1,5-hydrogen shift to afford a new type of trienes upon heating. Due to their high reactivity, these trienes would undergo subsequent pericyclic reactions based on the nature of the substituent group R: When R is an alkyl group, the intermediate 4a or 4b would undergo a further 1,7-hydrogen shift to afford a more stable conjugated triene 3; with R being phenyl or cyclopropyl group, the 1,7-hydrogen shift was inhibited and the 4-type conjugated triene would form a six-membered ring 5 via 6π-electrocyclization. Interestingly, introducing another C=C double bond into the triene intermediate (R = CH=CH2), the 18-type intermediate would undergo 8π-electrocyclization reaction to form an eight-membered ring. Such a transformation was also observed with 2-allyl-3-allenylcyclohex-2-enones. The deuterium-labeling mechanistic studies show that the alkyl groups at the allenyl moiety of 1 participated in the isomerization process via 1,7-hydrogen shifts between 18 A, 20A, and 29 A.
