97400-46-9Relevant academic research and scientific papers
Synthesis of a 4-Acylcyclohexa-2,5-dienone: 3,4-Dihydro-3,3,8a-trimethylnaphtalene-1,6(2H,8aH)-dione
Waring, Anthony John,Zaidi, Javid Hussain
, p. 631 - 640 (2007/10/02)
The synthesis is reported of 3,4-dihydro-3,3,8a-trimethylnaphtalene-1,6-(2H,8aH)-dione (11; R = Me).This is the first isolated 4-acylcyclohexa-2,5-dienone, a class of compounds postulated particularly as intermediates in the Fries and photo-Fries rearrangements.The dienone undergoes very easy acyl cleavage in the presence of bases or dilute acids, to form a phenolic acid (18).Similar cleavage, or a retro-Fries migration of the acyl group from the 4-position to the dienone ring oxygen, has prevented isolation of 4-acetyl-4-methylcyclohexa-2,5-dienone.Concentrated aqueous sulphuric acid causes rearrangement of the dienone to 3,4-dihydro-8-hydroxy-3,3,5-trimethylnaphtalen-1(2H)-one (13; R = Me), via recyclisation of 18.In trifluoroacetic acid solutions the same product (13, R = Me) is formed from the dienone by direct, formal dienone-phenol rearrangement.
