Changgui Zhao

Au-Catalyzed Piperidine Synthesis via Tandem Acyloxy Migration/Intramolecular [3+2] Cycloaddition of Enynyl Esters

An Au-catalyzed tandem protocol involving enynyl ester isomerization and subsequent intramolecular [3 + 2] cyclization has been developed. This strategy provides an efficient approach for the synthesis of polyfunctional piperidines, which are subunits of many bioactive molecules.

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.

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.

Rapid Construction of the [6-6-6-5] Tetracyclic Skeleton of the Daphniphyllum Alkaloid Daphenylline

You can call me Al: A concise route for construction of the [6-6-6-5] tetracyclic skeleton of daphenylline, a structurally novel Daphniphyllum alkaloid, has been developed with full stereocontrol in only 8 steps from two known fragments. This approach features an intramolecular [3+2] cycloaddition of a 2-azaallyl anion with an alkene to form the cis-fused AC rings.

Asymmetric Total Synthesis of Cladosporin and Isocladosporin

The first asymmetric total syntheses of cladosporin and isocladosporin were accomplished in 8 steps with 8% overall yield and 10 steps with 26% overall yield, respectively. The relative configuration of isocladosporin was determined via this total synthesis.

Fe-catalyzed direct dithioacetalization of aldehydes with 2-chloro-1,3-dithiane.

Present methods to synthesize 1,3-dithiane molecules require either harsh reaction conditions or highly specialized reagents. We have developed a catalytic dithioacetalization process that directly gains access to the corresponding 1,3-dithianes using aldehydes and 2-chloro-1,3-dithiane in a highly efficient manner. This methodology is beneficial due to mildness of the reaction conditions, and the dithioacetaliation process results in good to excellent yields by using 15 mol % of an iron catalyst.

Diels–Alder/Oxidative Aromatization Approach towards the All-Carbon DEF Tricyclic Skeleton of Daphenylline

Daphenylline is a recently isolated Daphniphyllum alkaloid with an unprecedented novel hexacyclic scaffold. In this study, the synthesis of the fused all-carbon DEF tricyclic skeleton of daphenylline has been accomplished. Key steps of the reported sequence involve Evans asymmetric allylation, aldol condensation, Diels-Alder reaction, and oxidative aromatization reactions. The developed strategy might lead to the total synthesis of daphenylline.

Total synthesis of (-)-Przewalskin B.

The first total synthesis of (-)-Przewalskin B has been accomplished with an intramolecular nucleophilic acyl substitution (INAS) reaction and an intramolecular aldol condensation as key steps.

Concise formal syntheses of the Amaryllidaceae alkaloids (±)-tazettine and (±)-6a-epipretazettine: construction of the core skeleton via tandem intramolecular oxidative Friedel-Crafts/aza-Michael reaction.

the MOST (2010CB833200);the NSFC (21125207;21072086;21102062);program 111;the Fundamental Research Funds for the Central Universities (lzujbky-2011-76)