Enantioselective total synthesis of (+)-labd-8(17)-ene-3β,15-diol and (−)-labd-8(17)-ene-3β,7α,15-triol

Aspects in the Total Syntheses of Higher Terpenoids Starting From Wieland–Miescher Ketone and Its Derivative: A Review

Synthetic studies of higher terpenoids starting from Wieland–Miescher ketone since 2012 have been compiled.

Pinacol Coupling Strategy for the Construction of the Bicyclo[6.4.1]tridecane Framework of Schiglautone A

The synthesis of the tricyclic carbon framework of schiglautone A (1) is reported herein. The generation of the bicyclo[6.4.1]tridecane 19 was accomplished via a SmI₂-mediated pinacol coupling of dialdehyde 18. The side chain in 18 was introduced using a selective 1,4-addition. A further key step of the synthesis was the homologation of a Wieland-Miescher ketone derivative to establish the 7-membered ring.

Theoretical Studies of Stereoselectivities of Intramolecular Aldol Cyclizations Catalyzed by Amino Acids

The effects of different amino acid catalysts and substrate substituents on the stereoselectivity of the title reactions have been studied with the aid of density functional theory methods. Experimental data available in the literature have been compiled. B3LYP/6-31G(d) calculations match the general experimental trends and provide useful insights into the origins of the variations in stereoselectivities. Acyclic primary amino acids allow a greater conformational flexibility in the aldol transition states compared with proline. This makes them poorer enantioselective catalysts with triketone substrates with a methyl ketone side chain. The steric repulsion upon substitution at the terminal methyl group increases the energy difference between anti- and syn-chairs with primary amino acid catalysts and, consequently, the stereoselectivities. Proline, in contrast, is a poor catalyst for the latter reactions because the substituent's steric bulkiness raises the activation energy of the favored C-C bond-forming pathway.

Theory of asymmetric organocatalysis of Aldol and related reactions: rationalizations and predictions

Computational studies have led to models to understand some classic and contemporary asymmetric reactions involving organocatalysts. The Hajos-Parrish-Eder-Sauer-Wiechert reaction and intermolecular aldol reactions as well as Mannich reactions and oxyaminations catalyzed by proline and other amino acids, and Diels-Alder reactions catalyzed by MacMillan's chiral amine organocatalysts have been studied with density functional theory. Quantitative predictions for several new catalysts and reactions are provided.