69043-86-3Relevant academic research and scientific papers
Regioselective reactions of 1,4,5-trihydroxy-9,10-anthraquinone
Broadbent, Douglas A.,Meschwitz, Wilfred,Stewart, John M.
, p. 2338 - 2341 (2007/10/02)
The regioselective alkylation of 1,4,5-trihydroxy-9,10-anthraquinone via reaction of its leuco compound is significant for the synthesis of anthracyclinones.In the presence of pyrrolidine in toluene solution, the leuco compound 3 selectively forms the 4-pyrrolidino enamine 11, which undergoes deamination to give 1,5-dihydroxy-9,10-anthraquinone.If an aldehyde is added, however, the enamine is alkylated, eventually yielding the 3-alkyl-1,4,5-trihydroxy-9,10-anthraquinone.Both of the above rections of 3 give high yields with 100percent regioselectivity.The enamine intermediate 11 has been trapped by oxidation to 4-pyrrolidino-1,5-dihydroxy-9,10-anthraquinone, which, after reduction, undergoes the same reactions as 3 giving either the alkylation or deamination product.The selective formation of 11 is explained terms of an enhancement of carbonyl group electrophilicity by a relay of hydrogen bonds.
