Development of a catalytic enantioselective synthesis of the guanacastepene and heptemerone tricyclic core

Dual Proton/Silver-Catalyzed Serial (5 + 2)-Cycloaddition and Nazarov Cyclization of (E)-2-Arylidene-3-hydroxyindanones with Conjugated Eneynes: Synthesis of Indanone-Fused Benzo[cd]azulenes

A one-pot step-economic tandem process involving (5 + 2)-cycloaddition and Nazarov cyclization reactions has been reported for the facile synthesis of indanone-fused benzo[cd]azulenes from (E)-2-arylidene-3-hydroxyindanones and conjugated eneynes. This highly regio- and stereoselective bisannulation reaction is enabled by dual silver and Brønsted acid catalysis and opens up a new avenue for the construction of important bicyclo[5.3.0]decane skeletons.

Gram-Scale Enantioselective Synthesis of (+)-Lucidumone

The first enantioselective total synthesis of (+)-lucidumone is described through a 13-step synthetic pathway (longest linear sequence). The key steps involve the formation of a bridged bicyclic lactone by an enantioselective inverse-electron-demand Diels-Alder cycloaddition, C-O bond formation to assemble two fragments, and a one-pot retro-[4 + 2]/[4 + 2] cycloaddition cascade. The synthesis is scalable, and more than one gram of natural product was synthesized in one batch.

Recent Advances in the Construction of Quaternary Stereocenters via Palladium-Catalyzed Decarboxylative Asymmetric Allylic Alkylation

Palladium-catalyzed decarboxylative asymmetric allylic alkylation (DAAA) provides an efficient and powerful strategy to construct quaternary stereocenters, which are widely present in biologically active natural products and approved drugs. In this short review, we summarize recent developments (since 2018) in the facile synthesis of quaternary stereocenters via DAAA methods. Several representative examples of the use of DAAA strategies for the total synthesis of complex natural products further demonstrate its synthetic potential in the realm of organic and medicinal chemistry.

1 Introduction

2 Construction of Quaternary Stereocenters via Palladium Catalyzed DAAA

3 Construction of Quaternary Stereocenters via Pd-Catalyzed Interceptive DAAA

4 Application of DAAA in Natural Product Synthesis

5 Conclusion

Construction of Structurally Rigid Azulen-6-ones via Migratory Rearrangement of Spirocycles and Their Photophysical Studies

We report the synthesis of polysubstituted 1,1,2,3-tetraarylazulen-6-ones through the ring opening and scaffold rearrangement of spirocycles in the presence of ferric chloride under ambient conditions. Control experiments shown that this reaction may proceeded through a radical cation mechanism and futher theoretical calculation revealed that the electronic distribution of the radical cation intermediate dominated this oxidative rearrangement instead of dehydrogenation. It is noteworthy that some interesting photophysical properties, including aggregation-induced emission, halochromism, and two-photon fluorescence, were discovered for the azulen-6-one 2a, making them to work as promising functional materials in optical-related fields.

Total Syntheses and Absolute Configuration Assignment of (+)-Sootepdienone, (-)-Jambolanin C, (-)-Jambolanin I, and (-)-Gibberodione

Total syntheses of the sesquiterpenes (+)-sootepdienone, (-)-jambolanin C, (-)-jambolanin I, and (-)-gibberodione have been accomplished in 10 steps each from R-(+)-pulegone, allowing assignment of the absolute configuration of the natural products. A key step in the synthetic pathways involves the one-carbon ring expansion of a cyclic allylic phosphonate to a substituted cycloheptenone by a tandem oxidative cleavage/intramolecular Horner-Wadsworth-Emmons reaction.

Brønsted-acid-catalyzed one-pot tandem annulation/[5 + 2]-cycloaddition of o-propargyl alcohol benzaldehydes with alkynes: regioselective and stereoselective synthesis of dibenzo[a,f]azulen-12-ones

The one-pot synthesis of dibenzo[a,f]azulen-12-ones has been established starting from o-propargyl alcohol benzaldehydes and alkynes.