Four-Step Total Synthesis of (+)-Yaoshanenolides A and B

A highly concise bioinspired four-step total synthesis of yaoshanenolides A and B possessing tricyclic spirolactone with an unusual 5'H-spiro-[bicyclo[2.2.2]-oct[2]ene-7,2'-furan]-5'-one scaffold is reported. This synthesis features high-yielding aldol-type addition of γ-butyrolactone on to the aldehyde, exocyclic olefination of lactone derivative using Eschenmoser's salt, and highly facial- and endo-selective [4 + 2]-cycloaddition of fully functionalized 5-methylene-2(5H)-furanone with natural R-(-)-α-phellandrene. The approach allows access to yaoshanenolides A and B in four linear steps in 11 and 13% overall yield.

O2-(6-Oxocyclohex-1-en-1-yl)methyl diazen-1-ium-1,2-diolates: a new class of nitric oxide donors activatable by GSH/GSTπ with both anti-proliferative and anti-metastatic activities against melanoma

3c, a new nitric oxide donor activatable by GSH/GSTπ, exhibits both anti-proliferative and anti-metastatic activities against melanoma.

Morita-Baylis-Hillman Reaction of β,β-Disubstituted Enones: An Enantioselective Organocatalytic Approach for the Synthesis of Cyclopenta[b]annulated Arenes and Heteroarenes

The first enantioselective organocatalytic intramolecular Morita-Baylis-Hillman (MBH) reaction of sterically highly demanding β,β-disubstituted enones is presented. The MBH reaction of β,β-disubstituted-α,β-unsaturated electron-withdrawing systems was previously considered to be unfeasible. Towards this end, designer substrates, which under simple and practical reaction conditions generate a variety of cyclopenta[b]annulated arenes and heteroarenes in excellent enantiopurities and near-quantitative yields in remarkably short reaction times, are described. The reason for the unusually facile nature of this reaction is attributed to the synergy guided and entropically favored intramolecular reaction. Further, this strategy provides easy access to a substantial number of bioactive natural products and pharmaceutically significant compounds.

4-(Dimethylamino)pyridine-catalysed iodolactonisation of γ,δ-unsaturated carboxylic acids

4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonization reactions of γ,δ-unsaturated carboxylic acids, affording γ-lactones, δ-lactones, or both.

Reactions of nitroxides XIII: Synthesis of the Morita-Baylis-Hillman adducts bearing a nitroxyl moiety using 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl as a starting compound, and DABCO and quinuclidine as catalysts

The Morita-Baylis-Hillman adducts bearing a nitroxyl moiety were synthesized from 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and aliphatic, aryl and heterocyclic aldehydes.

Bifunctional Polymeric Organocatalysts and Their Application in the Cooperative Catalysis of Morita–Baylis–Hillman Reactions

A series of soluble, non-cross-linked polystyrene-supported triphenylphosphane and 4-dimethylaminopyridine reagents were prepared. Some of these polymeric reagents contained either alkyl alcohol or phenol groups on the polymer backbone. The use of these materials as organocatalysts in a range of Morita-Baylis-Hillman reactions indicated that hydroxyl groups could participate in the reactions and accelerate product formation. In the cases examined, phenol groups were more effective than alkyl alcohol groups for catalyzing the reactions. This article is one of the first reports of the synthesis and use of non-natural, bifunctional polymeric reagents for use in organic synthesis in which both functional groups can cooperatively participate in the catalysis of reactions.

Ionic Liquid-Immobilized Quinuclidine-Catalyzed Morita−Baylis−Hillman Reactions

[reaction: see text] The ionic liquid-bound quinuclidine catalyzed Baylis-Hillman reactions were investigated. The IL-supported catalyst showed equally good catalytic activity as compared with its nonimmobilized counterpart. The corresponding Baylis-Hillman adducts were obtained in moderate to high yields in all the cases tested. The IL-supported quinuclidine can be readily recovered and reused six times without significant loss of catalytic activity.