In this review, we describe the many roles chalcogenides play as organocatalysts. Chalcogens, or the oxygen family, * To whom correspondence should be addressed. Phone: +00-44-1179546315. Fax:+00-44-117-9298611. E-mail: V.Aggarwal@Bristol.ac.uk. † University of Bristol. ‡ Current Address: Department of Biochemistry, University of Wisconsin s Madison, 433 Babcock Drive, Madison, Wisconsin 53706-1544. 5841 Chem. Rev. 2007, 107, 5841−5883

Chalcogenides as organocatalysts.

An efficient, highly convergent, stereocontrolled total synthesis of the potent antimitotic agent (+)-discodermolide (1) has been achieved on gram scale. Key elements of the successful strategy include (1) elaboration of three advanced fragments from a common precursor (CP) which embodies the repeating stereochemical triad of the discodermolide backbone, (2) σ-bond installation of the Z trisubstituted olefin, exploiting a modified Negishi cross-coupling reaction, (3) synthesis of a late-stage phosphonium salt utilizing high pressure, and (4) Wittig installation of the Z disubstituted olefin and the terminal (Z)-diene.

Evolution of a gram-scale synthesis of (+)-discodermolide

Carbon-carbon bond forming reactions mediated by silicon Lewis acids.

Iodine catalyzes efficient and chemoselective thioacetalization of carbonyl functions, transthioacetalization of O,O- and S,O-acetals and acylals.

Discodermolide is a marine natural product reported to inhibit the proliferation of T cells and exhibit immunosuppresive activity. Total syntheses of the natural antipode of discodermolide and several variants are reported. These studies provide reagents to investigate discodermolide's recently discovered ability to bind and stabilize microtubules in cells. Retrosynthetically, the polypropionate is divided into three fragments of approximately equal complexity. This modular strategy provides convergency in the synthesis and facilitates the preparation of discodermolide-based reagents.

Jung Ho Park

Papers

Selective removal of tetrahydropyranyl ethers in the presence of tert-butyldimethylsilyl ethers with magnesium bromide in ether

Selective Cleavage of Acetal-Type Ethers with Magnesium Bromide and Butyl Mercaptan in Diethyl Ether

Direct conversion of silyl ethers into alkyl bromides with boron tribromide

Palladium-catalyzed ring expansion of vinyl, oxaspirohexanes

A simple procedure for α-alkoxyalkylation of α,β-enones via pyridiniosilylation