Highly Selective Three??Step Synthesis of Rhein in Chloroaluminate Molten Salt: Preclusion of the Hayashi Rearrangement

V Gonnot, C Antheaume, M Nicolas…

Index: Gonnot, Vanessa; Antheaume, Cyril; Nicolas, Marc; Mioskowski, Charles; Baati, Rachid European Journal of Organic Chemistry, 2009 , # 35 p. 6205 - 6210

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Citation Number: 5

Abstract

Abstract An expeditious, three-step synthesis of rhein (2) was optimized starting from bis (N, N-diethyl)-5-methoxybenzene-1, 3-dicarboxamide. The key final step, involving deprotection/cyclization of ortho-benzoylbenzoic acid 9 in acidic chloroaluminate molten salts, yielded the desired natural product with high selectivity and good overall yield by precluding the competitive Hayashi rearrangement.(© Wiley-VCH Verlag GmbH & Co. ...