Selective synthesis of spiro and dispiro compounds using Mn(III)-based oxidation of tetracarbonyl compounds

Visible Light Mediated Organophotoredox Catalyzed Synthesis of Tetraketones Using Tertiary Amines as Alkyl Synthons

Eosin Y catalyzed syntheses of bioactive tetraketones using cyclic-1,3-diketones and tertiary amines as alkyl synthons under 18 W blue LED have been accomplished. The condition is very mild that uses air as a green oxidant and avoids previously used harsh conditions like high temperature. Diverse arrays of tertiary amines first undergo reductive quenching of excited photocatalysts to form iminium ions that upon subsequent attack by cyclic-1,3-diketones give rise to tetraketones. This method is demonstrated with 31 examples with yields up to 76%. The feasibility of this reaction in the presence of eosin Y catalyst under a solar condition is also demonstrated with significant examples.

Rearrangement of Methylenebis(cyclohexane-1,3-dione) Enols Induced by Mn(III)-Catalyzed Aerobic Oxidation

The Mn(III)-catalyzed aerobic oxidation of methylenebis(cyclohexane-1,3-dione) enols 1 resulted in 6a-hydroxy-2,3,4,6a,7,8,9,10a-octahydro-1H-benzo[c]chromene-1,6,10-triones 3 during the formation of 4,5,8,10,11,12-hexahydro-2H-benzo[b]oxecine-2,6,7,9(3H)-tetraones 2. The mechanism for the formation of 3 was proposed on the basis of the isolation of intermediates 2, which were transformed into 3 under Claisen and retro-Claisen conditions.