An expedient synthesis of salviadione

Transition Metal Catalyzed Reductive Cyclization Reactions of Nitroarenes and Nitroalkenes

“…The cyclization of an o‐ nitrostyrene was also employed as a step in the synthesis of salviadione (Scheme ) . Attempted cyclization of the quinole (lower reaction in the scheme) resulted in the complete consumption of the reagent, but only gave small amounts of the desired dione, accompanied by a complex mixture of compounds.…”

“…[121] The cyclization of an o-nitrostyrene was also employed as a step in the synthesis of salviadione (Scheme 25). [122] Attempted cyclization of the quinole (lower reaction in the scheme) resulted in the complete consumption of the reagent, but only gave small amounts of the desired dione, accompanied by a complex mixture of compounds. On the other hand, reaction of the corresponding phenol or anisole successfully gave an indole from which the dione could be obtained in good yields by oxidation with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone), when the phenol derivative was employed.…”

Biomimetic synthesis of the natural product salviadione and its hybrids: discovery of tissue-specific anti-inflammatory agents for acute lung injury

“…Although the tetracyclic alkaloid 5 was first synthesized in 2011 by Söderberg and co-workers with a palladium-catalyzed CO-mediated reductive N-heterocyclization as the key step (Fig. 2a),11 long reaction steps and harsh reaction conditions make this approach unfeasible for the construction of 5 on a large scale. Since both compounds 5 and 4 were isolated from the same plant, it is likely that 5 is biogenetically derived from 4 under an ammonia atmosphere (Fig.…”

Total synthesis of the tetracyclic indole alkaloid ht-13-A

“…Palladium catalyzed reductive N-heterocyclization of 10 in the presence of carbon monoxide gave the expected tetracyclic indole 11. 10,11 Finally, the methoxycarbonyl group was reduced to a methyl group using sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al) in toluene affording ht-13-A in high isolated yield. The 1 H and 13 C NMR, IR, HRMS, melting point and optical rotation data of synthetic ht-13-A were identical to the literature values of the compound isolatated by Kamiguchi and Yasui.…”