67116-22-7Relevant articles and documents
Transition Metal-Catalyzed Oxidations, 6. Total Synthesis of Hallachrome and Related 1,2-Anthraquinones
Krohn, Carsten,Khanbabaee, Karamali
, p. 905 - 910 (2007/10/02)
9,10-Anthraquinones 3b-3k are prepared by Diels-Alder reaction of juglone (5a) and 7-methyljuglone (5b) with the dienes 4a and 4b, then reduced to the corresponding 1-anthracenols 2b-2d, 2f and 2i that are immediately oxygenated to the ortho-anthraquinones 1b-1d, 1f and 1i with *py*HMPT.The 1,2-anthraquinones dimerize in solution or upon BBr3 treatment.The naturally occurring 1,2-anthraquinone hallachrome (1a) is prepared by selective protection of the bisphenol 3h as monosilyl ether 3i, oxygenation to the silylated ortho-anthraquinone 1i and fluoride-mediated deprotection to 1a. Key words: Hallachrome; 1,2-anthraquinones; 9,10-anthraquinones; oxygenation; 1-anthracenols; Mimoun complex.
REACTIONS OF KETENE ACETALS-14; THE USE OF SIMPLE MIXED VINYLKETENE ACETALS IN THE ANNULATION OF QUINONES
Savard, Jacques,Brassard, Paul
, p. 3455 - 3464 (2007/10/02)
α,β- and β,γ-unsaturated esters can be converted by strong base and chlorotrimethylsilane to the corresponding mixed vinylketene acetals which are shown to be particularly useful and generally applicable reagents for the regiospecific annulation of halogenoquinones.The reaction proceeds readily with a variety of substrates including benzoquinones.
