Won-Hun Ham

Asymmetric Synthesis of (−)-Swainsonine

We report a new asymmetric synthetic method for (-)-swainsonine utilizing a chiral oxazoline precursor. The key features in this strategy are the diastereoselective oxazoline formation reaction catalyzed by palladium(0), diasteroselective dihydroxylation, and the stereocontrolled allylation reaction with TiCl(4).

A formal total synthesis of (±)-anatoxin-a by an intramolecular Pd-catalyzed aminocarbonylation reaction

9-Azabicyclo[4.2.1]nonane skeleton 3a was prepared by intramolecular aminocarbonylation of 2a catalyzed by palladium. In three steps 3a was transformed into 8 which had previously been transformed into anatoxin-a, thus completing the formal total synthesis.

A highly stereocontrolled asymmetric synthesis of the Taxol C-13 side chain; (4S, 5R)-2,4-diphenyloxazoline-5-carboxylic acid

Abstract A stereoselective synthesis of (4S, 5R)-2,4-diphenyloxazoline-5-carboxylic acid, a precursor of the Taxol C-13 side chain was achieved using palladium-catalyzed oxazoline formation reaction from commercially available amino acid.

Total synthesis of myriocin

Abstract A concise, stereocontrolled synthesis of myriocin was achieved. Key features involve diastereoselective oxazoline formation catalyzed by palladium(0), MgBr 2 -promoted allylic stannane addition, and palladium(0)-catalyzed coupling of a vinyl iodide with an organozinc reagent.

A formal total synthesis of (±)-ferruginine by Pd-catalyzed intramolecular aminocarbonylation

Abstract A practical and efficient synthetic route to the neuroactive alkaloid ferruginine has been developed. 8-Azabicyclo[3.2.1]octane skeleton 4 was prepared in one step by intramolecular aminocarbonylation of 3 catalyzed by palladium.

Stereoselective synthesis of L-threo-sphingosine, L-ffrreo-sphinganine, D-threo-sphingosine, and D-threo-sphinganinevia oxazoline formation and olefin cross-metathesis; potent protein kinase C inhibitor analogues

In this study, we explored a convenient and concise route for synthesis of L-threo-sphin-gosine, D-threo sphingosine, L-threo-sphinganine and D-threo-sphinganine from commercially available L- or D-serine. The key steps are the simple preparation oftrans-oxazoline and inte-rmolecular olefin cross metathesis.

Stereoselective synthesis of (+)-polyoxamic acid based on the synthesis of chiral oxazine

A concise, stereocontrolled synthesis of (+)-polyoxamic acid was achieved. Starting from trans-oxazoline as a chiral building block, the key step involves diastereoselective oxazine formation catalyzed by palladium(0).

Intramolecular TiCl 4 -mediated cyclization reaction of β-hydroxy alkynyl acetals

Abstract Intramolecular TiCl4-mediated cyclization reaction of 1,1-dimethoxy-3-hydroxy-hex-5-yne derivatives produced anti-1-hydroxy-3-methoxy-cyclohex-5-ene derivatives with high diastereoselectivity via antiperiplanar manner on pseudo six-membered chair like conformation (transition state A).

A concise synthesis of a promising protein kinase C inhibitor: D-erythro-sphingosine

In this study, we explored a convenient and concise route for synthesis ofD- erythro- sphin- gosine1 from commercially available and cheap L-serine. The key steps are simple preparation of amino ketone5 from Weinreb amide3 and high diastereoselective reduction of amino ketone5 to give the naturalerythro- (anti- ) isomer.

Diastereoselective synthesis ofanti-1,2-aminoalcohol by palladium(ll) catalyzed aza-claisen rearrangement

In this study, a highly diastereoselective synthesis of antiA,2-aminoalcohol was explored starting from L-amino acids as chiral sources. The higher yield and diastereoselectivity was shown when the aza-Claisen rearrangement was performed with allylic trichloroacetimidate6a in the presence of palldium(ll) catalyst.