Synthesis of Triazole-Linked Pseudo-Starch Fragments.

Total syntheses of phorboxazole A and analogues have been developed that rely upon the convergent coupling of three fragments via biomimetically inspired de novo oxazole formation.

T1 - A convergent approach to the formal total synthesis of hemibrevetoxin B

A convergent stereocontrolled total synthesis of (+)-tautomycin (1), a specific inhibitor of protein serine/threonine phosphatases, has been achieved through an esterification of the C1.-C7. fragment A'74 with the C1-C26 fragment B'76 by a modified Yamaguchi method and an aldol reaction of the C17-C26 fragment C 5 with the C1-C16 fragment D 6 using LDA as key steps. The fragments 5 and 6 have been constructed in a stereocontrolled manner, respectively.


T., Chemoenzymatic synthesis of triazole-linked glycopeptides.

Copper-Catalyzed Synthesis of -Sulfonyl-1,2,3-Triazoles: Controlling Selectivity.

N2 - A convergent stereocontrolled total synthesis of (+)-tautomycin (1), a specific inhibitor of protein serine/threonine phosphatases, has been achieved through an esterification of the C1.-C7. fragment A'74 with the C1-C26 fragment B'76 by a modified Yamaguchi method and an aldol reaction of the C17-C26 fragment C 5 with the C1-C16 fragment D 6 using LDA as key steps. The fragments 5 and 6 have been constructed in a stereocontrolled manner, respectively.


A Highly Convergent and Biomimetic Total Synthesis of Portentol

A convergent total synthesis of (−)-nahuoic acid Ci(Bii) (3), a novel -decalin polyketide, has been achieved. Key synthetic transformations include Type II Anion Relay Chemistry (ARC) to construct the polyol chain, a Ti-catalyzed asymmetric Diels–Alder reaction to generate the -decalin skeleton, and a late-stage large fragment union exploiting a Micalizio alkoxide-directed alkyne–alkene coupling tactic.

The total synthesis of strychnine was accomplished by American ..

A highly convergent, enantioselective total synthesis of brevetoxin A is reported. The development of a [X+ 2+ X] Horner-Wadsworth-Emmons/ cyclodehydration/reductive etherification convergent coupling strategy allowed a unified approach to the synthesis of two advanced tetracy-clic fragments from four cyclic ether subunits. The Horner-Wittig coupling of the two tetracyclic fragments provid-ed substrates that were explored for reductive etherification, the success of which delivered a late-stage tetraol intermediate. The tetraol was converted to the natural product through an expeditious selective oxidative process followed by methylenation.

1994 A convergent total synthesis of ..

The total synthesis of (+)-lithospermic acid is reported, which exploits two successive C−H activation reactions as key steps. Rh-catalyzed carbene C−H insertion reaction utilizing Davies’s catalyst was used to forge dihydrobenzofuran core, and a late-stage intermolecular C−H olefination coupled the olefin unit with the dihydrobenzofuran core to construct the molecule in a highly convergent manner.

A convergent route for the total synthesis of the eleuthesides …

Rational-design and unexpected discovery of new reactions through C-H activation Our program centers around the discovery of catalytic carbon-carbon and carbon-heteroatom bond forming reactions based on C-H activation. Target transformations are selected to enable 1) the use of simple and abundant starting materials such as aliphatic acids, amines and alcohols, and 2) disconnections that drastically shorten the synthesis of drug molecules or a major class of biologically active compounds. Ultimately, we hope to develop catalytic reactions to parallel enzymatic transformations in terms of reactivity and selectivity. To achieve this goal, our research activities are directed towards the following main aspects: C-H activation, sustainable catalysis, asymmetric catalysis and synthetic applications.Major components of training for students are organometallic chemistry, asymmetric catalysis (synthesis and characterization of organometallic complexes as catalysts or intermediates; ligand design for chiral control or acceleration) and organic synthesis (in the context of drug discovery and natural product synthesis). We collaborate extensively with computational groups via NSF center (Professor Jamal Musaev, Emory University, Professor Ken Houk, UCLA), as well as pharmaceutical and agrochemical industry (BMS and Syngenta) and Aldrich. We have research projects on the following topics: C-H activation (how to cleave C-H bonds without using forceful conditions?); Catalysis (how to close catalytic cycles under practical conditions?); and Synthetic applications (how to shorten synthetic routes for natural products and drug molecules?).