We report concise asymmetric total syntheses of tetracyclic marine alkaloids (+)-agelastatin A and (+)-agelastatin B using a cationic cyclization-based approach, which features straightforward transformations with cost-effective chemicals and reagents.Download high-res image (180KB)Download full-size image

Hexafluoropropylene oxide (HFPO) oligomers are toxic, bioaccumulative, and persistent organic pollutants (POPs). Consuming the harmful chemicals to prevent them from releasing to nature is of serious significance as far as both natural environments and human health are concerned. In this study, investigation on degradation of HFPO oligomers to pentafluoropropionyl fluoride (PPF), a valuable industrial chemical, is reported. Different combinations of alkali metal fluoride in either diglyme or tetraglyme under both flask and batch autoclave conditions were examined. Under the optimal reaction conditions, HFPO oligomers (n = 2–10) were completely degraded to PPF in over 90% yield. Reactions on 200 g scale were tested and no deduction of efficiency was observed, which indicates the potential for practical industrial application of this chemistry.Degradation of HFPO oligomers, persistent organic pollutants harmful to human and natural environment, to pentafluoropropionyl fluoride (PPF), a valuable industrial chemical widely used for manufacture of important chemical products, such as Novec 1230, PPVE, GenX etc. is reported using CsF/tetraglyme as catalytic system under both flask and autoclave conditions.

Total syntheses of terpenoids play an essential role in the development of synthetic organic chemistry and medicinal science. Chinese synthetic community has made more and more profound contribution to this field and has gradually grown into a major force in the world over the past years. In this review, we shall celebrate the achievement by surveying the recent terpenoid syntheses from China since 2010.

A concise total synthesis of mersicarpine is achieved by exploiting a cyclic carbamate for generation of a tertiary carbocation. The key step involves intramolecular Friedel–Crafts alkylation with this carbocation for the construction of a quaternary carbon center and a subsequent oxidation and cyclization cascade for the formation of a seven-membered cyclic imine. The chemistry allowed for a rapid one-pot synthesis of mersicarpine from a simple intermediate using straightforward chemical operations.

Total syntheses of omphadiol and pyxidatol C, two isomeric africanane sesquiterpenes sharing identical 5-7-3 tricyclic carbon skeletons yet containing distinct oxidation patterns, are reported. The trans-fused 5,7-carbocycles in the terpenoids characterized by specific oxidation patterns were derived from a readily available cis-fused 5,7-carbocyclic common intermediate.

A concise and scalable synthesis of a cis-fused bicyclo[5.3.0]decane ring system has been developed for the total synthesis of echinopines. The core of the natural products was constructed efficiently through an intramolecular 1,3-dipolar cycloaddition and ring contraction strategy.

A quick access to the core of dihydroindole alkaloid mersicarpine was developed based on straightforward transformations from readily available and inexpensive starting materials. The synthetic route features an aldol reaction, a Beckmann rearrangement for the synthesis of the δ-lactam, an intramolecular SNAr strategy for indoxyl heterocycle formation, and in situ autoxidation of indoxyl intermediate. The new strategy offered an alternative approach for the formation of an oxidized indoxyl moiety, which could potentially have a wider application in the total synthesis of indole alkaloids containing apparent or masked indoxyl moieties.

An efficient and scalable synthesis of the ABC ring system common to the calyciphylline A-type alkaloids has been developed. The tricyclic core of the alkaloids features a bowl-shaped [6–6–5] skeleton with five stereogenic centers including an all-carbon quaternary center. It was constructed rapidly from a readily available carvone derivative through a seven-step sequence involving an aza-Michael addition and Pd-catalyzed enolate α-vinylation as key steps.

Selective syntheses of leuconolam, leuconoxine, and mersicarpine alkaloids bearing distinctive core structures were achieved through Staudinger reactions using a common intermediate. In the key cyclization step, water functioned like a switch to control which core structure to produce. The chemistry allowed for selective syntheses of the group of alkaloids from a simple intermediate through straightforward chemical operations.