Xingang Xie

Concise formal synthesis of (+)-neopeltolide.

A concise formal synthesis of (+)-neopeltolide (1) has been accomplished. The synthesis demonstrated high atom efficiency employing only one step of functional group protection. Key steps involved iridium-catalyzed double asymmetric carbonyl allylation, palladium-catalyzed intramolecular alkoxycarbonylation, ruthenium-catalyzed olefin isomerization, and ring-closing metathesis.

Visible-Light-Promoted Dual C–C Bond Formations of Alkynoates via a Domino Radical Addition/Cyclization Reaction: A Synthesis of Coumarins

A visible-light-promoted, mild, and direct difunctionalization of alkynoates has been accomplished. This procedure provides a new strategy toward synthesis of the coumarin core structure by photoredox-mediated oxidation to generate the α-oxo radical, which supervenes a domino radical addition/cyclization reaction in moderate to good yields with high regioselectivity at ambient temperature.

Total syntheses of Tardioxopiperazine A, Isoechinulin A, and Variecolorin C.

First total syntheses of the isoechinulin-type alkaloids: Tardioxopiperazine A, Isoechinulin A, and Variecolorin C have been achieved from a common key intermediate 5, which was derived from a regiocontrolled Stille cross-coupling reaction of an allylindium reagent.

Gold-Catalyzed 1,2-Acyloxy Migration/Intramolecular [3+2] 1,3-Dipolar Cycloaddtion Cascade Reaction: An Efficient Strategy for Syntheses of Medium-Sized-Ring Ethers and Amines

A highly efficient strategy for the formation of medium-sized-ring ethers and amines based on a gold-catalyzed cascade reaction, involving enynyl ester isomerization and intramolecular [3+2] cyclization, has been developed. Various multisubstituted medium-sized-ring unsaturated ethers and amines were obtained through this transformation. This method represents one of the relatively few transition metal catalyzed intramolecular cycloaddition reactions for medium-sized ring synthesis.

Iron-catalyzed radical oxidative coupling reaction of aryl olefins with 1,3-dithiane.

An alternative method to an iron-catalyzed radical oxidative cross-coupling reaction followed by 2-chloro-1,3-dithiane and aryl olefins for the synthesis of β-chloro substituent 1,3-dithiane products is presented. The described method has the advantage of mildness of the reaction conditions and tolerates a variety of functional groups. Preliminary mechanistic studies have confirmed the first example of a coupling of 1,3-dithiane with unactivated alkenes that proceeds via an iron-catalyzed oxidative radical intermediate along the reaction pathway.

Tandem Oxidative Dearomatization/Intramolecular Diels–Alder Reaction for Construction of the Tricyclic Core of Palhinine A

A concise construction of the 6/6/5 tricyclic core of Lycopodium alkaloid palhinine A (1) has been accomplished. The developed synthetic strategy featured a tandem oxidative dearomatization/intramolecular Diels-Alder reaction to construct C/D rings and an intramolecular 5-exo-trig radical cyclization to install the B ring of palhinine A (1). The developed approach paves the way for the total synthesis of palhinine A (1).

Asymmetric Total Synthesis of Fusarentin 6-Methyl Ether and Its Biomimetic Transformation into Fusarentin 6,7-Dimethyl Ether, 7-O-Demethylmonocerin, and (+)-Monocerin

A concise asymmetric total synthesis of a fusarentin ether (1) with sequential biomimetic transformation to its analogues fusarentin 6,7-dimethyl ether (2), 7-O-demethylmonocerin (3), and (+)-monocerin (4) has been accomplished. The cis-fused furobenzopyranones of 7-O-demethylmonocerin (3) and (+)-monocerin (4) were efficiently constructed via an intramolecular nucleophilic trapping of a quinonemethide intermediate, which was obtained by benzylic oxidation of fusarentin 6-methyl ether (1) using hypervalent iodine reagent.

First enantioselective synthesis of daphneticin and its regioisomer

An enantioselective total synthesis of chiral daphneticin and its regioisomer is reported for the first time.

Bioinspired Collective Syntheses of Iboga-Type Indole Alkaloids

We present the application of a bioinspired collective synthesis strategy in the total syntheses of seven iboga-type indole alkaloids: (±)-tabertinggine, (±)-ibogamine, (±)-ibogaine, (±)-ibogaine hydroxyindolenine, (±)-3-oxoibogaine hydroxyindolenine, (±)-iboluteine, and (±)-ervaoffines D. In particular, tabertinggine and its congeners serve as iboga precursors for the subsequent biomimetic transformations into other iboga-type alkaloids.

Enantioselective total synthesis of (-)-walsucochin B.

The first enantioselective total synthesis of the structurally unique nortriterpenoid (-)-walsucochin B has been accomplished through the cationic polyolefin cyclization initiated by chiral epoxide. The core framework and the stereocenters in the natural product were all constructed in this step. A site-selective, late-stage free-radical halogenation and Seyferth-Gilbert homologation was adopted to install the acetylene moiety to synthesize the phenylacetylene. The absolute configuration of walsucochin B was confirmed through enantioselective total synthesis.