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A newly developed strategy consisting of allylsilane ring-closing metathesis and subsequent SE' electrophilic desilylation (allylsilane RCM/SE') to construct exo-methylidenecycloalkanes is described. The method helped to identified a novel metal alkylidene-promoted deallylation reaction of terminal 1,4-dienes and provided a possible mechanism for the unexpected deallylation reaction of 1,4-dienes.

The enantioselective synthesis of a member of the chlorosulfolipid family of natural products is described. The polar substituents of malhamensilipin A are introduced with high stereoselectivity and the unique (E)-chlorovinyl sulfate is created by a chemo-, regio-, and stereoselective E2 elimination of HCl in a reaction, which has a counterpart in the biosynthesis of the natural product.

A general strategy is described for the synthesis of exo-methylidenecycloalkanes and ring-closing metathesis of allylsilanes has provided intermediates that can be protodesilylated with alkene transposition to afford the exocyclic alkene. These two reactivities are showcased in short syntheses of the sesquiterpene natural products teucladiol and poitediol.

The relative stereochemistry of the major chlorosulfolipid of the chrysophyte alga Ochromonas danica (danicalipin A) is described. The synthesis strategy is applicable to other chlorosulfolipids and has provided access to sufficient materials for analyzing lipid's properties and function in membranes.

The rearrangement of Zincke aldehydes to Z-[alpha],[beta],[gamma],[delta]-unsaturated amides has led to the discovery of a thermally induced pericyclic cascade rearrangement that has converted Zincke aldehydes derived from allylic and homoallylic amines into polycyclic lactams. The studies have shown that the rigid polycyclic products are available in only two steps from pyridinium salts and the allylic or homoallylic secondary amines.

An efficient anionic bicyclization of tryptamine-derived Zincke aldehydes has formed a basis for a three-step route to the tetracyclic ABCE core of many Strychnos, Aspidosperma and Iboga alkaloids. This reaction is shown in a five-step synthesis of the Strychnos alkaloid norfluorocurarine from trpytamine and pyridine.

All four diastereomers of 3,4-dichloro-2-pentanol are prepared by anti-dichlorination of the precursor allylic alcohols and their stereochemistry is evaluated by X-ray crystallographic analysis of tosylate derivatives. Complete NMR data has facilitated structural elucidation and synthesis studies on the chlorosulfolipid family of natural products, such as malhamensilipin A.

Dichlorination of (Z)-allylic trichloroacetates has efficiently and stereoselectively generated the syn,syn hydroxydichloride strereotriad that is prevalent in the polyclorinated sulfolipid class of natural products. The dichlorination of a (Z)-allylic chlorohydrin produced a stereotetrad present in one of the chlorosulfolipids with high selectivity.

A new method for the stereoselective synthesis of Z-[alpha],[beta],[gamma],[delta]-unsaturated amides is reported. The approach is based on a pericyclic cascade rearrangement of donor-acceptor dienes known as Zincke aldehydes.

The interaction of cyclostreptin with tubulin polymer by examining its effects on the binding of the fluorescent paclitaxel analogue Flutax-2 to glutaraldehyde-fixed microtubules is explored. Compared with paclitaxel and docetaxel, cyclostreptin had decreased affinity for polymer at 4 degree Celsius but not at 35 degree Celsius.

The first catalytic asymmetric conjugate addition of an oxygen-centered nucleophile to unsaturated carboxylic acid derivatives is developed. Findings show that when combined with efficient N-O bond hydrogenolysis, the (salen)aluminum-catalyzed reaction enables the net enantioselective hydration of electron-deficient olefins with no need for purification of the intermediate oxime ethers.

An efficient and scalable synthesis of both enantiomeric forms of the cytotoxic natural product FR182877 is developed. The reactivity of the strained, bridgehead olefin of the secondary metabolite with biologically relevant nucleophiles is described.

Shellfish toxins cause illness and death in people who ingest the tainted organisms, and can affect populations of fish and other marine animals (1). Perhaps surprisingly, these compounds also have [...]

Research has been conducted on the complex hexacyclic ring system with the stereocenters and a strained bridgehead alkene. The synthesis of the alkene structure has been carried out and the results are reported.

Two synthesis designs for the diterpenoid crotogoudin are discussed, and efforts to achieve each are described. First, a Cope rearrangement/intramolecular Diels-Alder cascade reaction was investigated. Second, a bioinspired sequence of cationic bicyclization and A-ring oxidative fragmentation set-up for a lactonization induced by a phenolic oxidation, ultimately providing a tricyclic intermediate that required only installation of the bridging ring of the salient bicyclo[2.2.2]octane system. This last endeavor was fraught with difficulty, but did lead to the development of conditions for cyclization of related keto-alkenes via manganese(III)-based radical chemistry. [ABSTRACT FROM AUTHOR]