Practical synthesis of ECH and epoxyquinols A and B from (-)-shikimic acid

An efficient synthesis of ECH, epoxyquinols A and B, and two bioactive analogs EqM and RKTS-33 has been completed starting from (-)-shikimic acid. Rapid establishment of the desired epoxyquinol core is facilitated through a key allylic oxidation with high stereoselectivity, which is achieved by fine tuning the cyclohexene substrate structure and reaction conditions.

Diastereomerically pure rarely functionalized alkenoyl dihydropyrans, 1,6-diketones, and cyclopentanes from acetylene gas and ketones

Alkenoyl dihydropyrans stereoselectively assembled from acetylene gas, ketones and aldehydes in two steps are diastereoselectively transformed into difficult-to-access, rarely functionalized 1,6-diketones and cyclopentanes.

Synthesis of heterocyclic compounds through nucleophilic phosphine catalysis

Nucleophilic phosphine catalysis is a practical and powerful tool for the synthesis of various heterocyclic compounds with the advantages of environmentally friendly, metal-free, and mild reaction conditions. The present report summarizes the construction of four to eight-membered heterocyclic compounds containing nitrogen, oxygen and sulphur atoms through phosphine-catalyzed intramolecular annulations and intermolecular [2+2], [3+2], [4+1], [3+1+1], [5+1], [4+2], [2+2+2], [3+3], [4+3] and [3+2+3] annulations of electron-deficient alkenes, allenes, alkynes and Morita-Baylis-Hillman carbonates.

Understanding the mechanisms, regioselectivies and enantioselectivities of the DMAP-catalyzed [2 + 4] cycloaddition of γ-methyl allenoate and phenyl(phenyldiazenyl)methanone

DMAP-catalyzed [2 + 4] cycloaddition reaction.

Irreversible endo-selective diels-alder reactions of substituted alkoxyfurans: a general synthesis of endo-cantharimides

The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead-like properties for medicinal chemistry programs. Furthermore, the electron-rich furans are shown to react with a variety of alternative dienophiles to generate 7-oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3-alkoxy group on a furan Diels-Alder reaction.

Asymmetric synthesis of chiral cycloalkenone derivatives via palladium catalysis

The palladium-catalyzed oxidative desymmetrization of meso dibenzoates yields γ-benzoyloxy cycloalkenones in good yields and with excellent levels of enantioselectivity. These compounds serve as precursors to a broad range of substituted cycloalkenones, including well-established synthetic building blocks and elaborated cycloalkanone derivatives. The ability to prepare both enantiomers of the oxidative desymmetrization products enables a unified strategy toward stereochemically diverse epoxyquinoid natural products.

Total synthsis of (+)-ambuic acid: α-bromination with 1,2-dibromotetrachloroethane

Total synthesis of (+)-ambuic acid has been accomplished from the readily available stereocontrolled Diels-Alder adduct of cyclopentadiene and iodo-1,4-benzoquinone monoketal through an efficient series of steps. A new method for the highly commendable synthesis of α-brominated Diels-Alder adduct is described.

Tandem enyne metathesis-metallotropic [1,3]-shift for a concise total syntheses of (+)-asperpentyn, (-)-harveynone, and (-)-tricholomenyn A

A tandem reaction sequence involving relay metathesis-induced enyne RCM and metallotropic [1,3]-shift is an effective tool to construct cyclic alkenes with embedded 1,5-dien-3-yne moieties from acyclic precursors containing a 1,3-diyne. Total syntheses of (+)-asperpentyn, (-)-harveynone, and (-)-tricholomenyn A have been accomplished by implementing this metathesis-based tandem reaction sequence as the key step.