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Au(I)-Catalyzed Cyclization of Methyl 2-(2-Alkynylphenylethynyl) Benzoates to 6H-Dibenzo[c,h]chromen-6-ones and Synthesis of Arnottin IHsu, Chia-Ling 02 July 2012 (has links)
Gold catalysts have the characteristic of promoting nucleophilic reaction. The cyclization reaction of enediynes catalyzed by gold activated by silver in toluene at 100oC to give 6H-dibenzo[c,h]chromen-6-ones (63), 6H-benzo[c]chromen-6-one (66) and Arnottin I (10) is described.
Treatment of enediynes (61¡B65) with 5 mol% of Ph3PAuCl and 10 mol% of AgSbF6 in toluene at 100oC gave 6H-dibenzo[c,h]chromen-6-ones (63) and 6H-benzo[c]chromen-6-one (66) in good yield. In addition to using gold catalyst, electrophilic reagents employed in the reaction caused one cyclization instead of two cyclization. Furthemore, a mechanistic study and GC-MS data showed that the toluene could participate in the reaction.
Enediynes (73) can be synthesized by a series of organic synthesis with few steps. Treatment of enediynes (73) with 5 mol% of Ph3PAuCl and 10 mol% of AgSbF6 in toluene at 100oC gave natural product-Arnottin I (10).
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