Enone

About: Enone is a research topic. Over the lifetime, 5683 publications have been published within this topic receiving 102109 citations.

Efficient visible light photocatalysis of [2+2] enone cycloadditions.

Abstract: We report that Ru(bipy)3Cl2 can serve as a visible light photocatalyst for [2+2] enone cycloadditions. A variety of aryl enones participate readily in the reaction, and the diastereoselectivity in the formation of the cyclobutane products is excellent. We propose a mechanism in which a photogenerated Ru(bipy)3+ complex promotes one-electron reduction of the enone substrate, which undergoes subsequent radical anion cycloaddition. The efficiency of this process is extremely high, which allows rapid, high-yielding [2+2] cyclizations to be conducted using incident sunlight as the only source of irradiation.

Catalytic asymmetric reductive Michael cyclization.

Abstract: A highly efficient and chemo-, regio-, diastereo-, and enantioselective organocatalytic tandem conjugate reduction−Michael cyclization of enal enones has been developed. Accordingly, treating the enal enone with a Hantzsch dihydropyridine in the presence of a catalytic amount of an imidazolidinone organocatalyst provides cyclic keto aldehydes in high yields and enantiomeric excesses. The reaction works well with aliphatic and aromatic substrates in the synthesis of five- and six-membered carbacyclic derivatives.

Platinum- and Acid-Catalyzed Enyne Metathesis Reactions: Mechanistic Studies and Applications to the Syntheses of Streptorubin B and Metacycloprodigiosin

Abstract: Formal total syntheses of the antibiotics metacycloprodigiosin (2) and streptorubin B (3) are described, which are known to exhibit promising immunomodulating properties. The key step en route to their meta-bridged pyrrole core structures 5 and 7, respectively, consists of a metathesis reaction of electron-deficient enynes catalyzed by either platinum halides, hard Lewis acids, or HBF4. This transformation expands the pre-existing cycloalkene of the substrates by two C atoms, forges the bicyclic pyrrolophane structure of the targets, and simultaneously forms a bridgehead alkene function. The products of this skeletal rearrangement are converted into the targets by a sequence comprising (i) a stepwise reduction of their enone entity to the corresponding saturated alcohols and (ii) an aromatization of the N-tosylated dihydropyrroles 20 and 34 thus obtained via elimination of potassium sulfinate on exposure to KAPA (potassium 3-aminopropylamide). A careful analysis of the minor byproducts formed in the enyne...