C-linked neuraminic acid disaccharide was synthesized in a diastereoselective manner from a sulfone donor and aldehyde acceptor, which was protected as a propargyl ether, through a samarium-mediated coupling reaction. The resulting disaccharide has acetal and phenyl sulfide functional groups that can be easily converted into aldehyde and phenyl sulfone groups by photolysis and oxidation reactio...

Taxine B (3), isolated from the dried needles of Taxus baccata, was converted into six novel 7-deoxypaclitaxel analogs, 20, 21a,b, and 23-25, that have structural changes at C1, C2, and C4. A method for the introduction of the benzoyl function at C2, via a benzylidene acetal at C1-C2, will be revealed. All compounds showed very little or no measurable cytotoxic activity against some well-charac...

The cycloisomerization reactions of allenes bearing cyclic acetal, thioacetal and dithioacetal subunits, when triggered either by the catalytic action of AgSbF6 or by one equiv. of CF3COOH, gave rise to four different classes of indeno-fused 1,4-dioxa, oxathia and dithia heterocycles, in most cases as a single diastereomer. Acyclic acetals and dithioacetals are also suitable starting materials ...

CuCl2-mediated intramolecular C-H/C-H cross-dehydrogenative coupling (CDC) of thioalkyl-substituted α-acetyl or α-aroyl ketene N,S-acetals afforded 2-thioalkyl indoles. Tunable C-S bond transformations of the resultant indoles led to highly functionalized N-heterocyclic compounds. A β-thioalkyl is necessary to activate the N,S-acetal substrate and enable the CDC reaction to occur, and the relev...

We document a route for the synthesis of a densely functionalized spiro-fused 2,5-cyclohexadienone as an intermediate for the synthesis of resineferatoxin. The strategy is based on an unprecedented diastereoselective, intramolecular phenol para-alkylation to a cross-conjugated cyclohexadienone. In the course of these synthetic studies we developed rapid access to a chiral nitrile possessing a q...

Four new and rare iridoid glucosides, cornusfuroside A-D (1-4), containing the furan ring were identified from water extract of the fruit of Cornus officinalis. These new chemical structures were determined through extensive spectroscopic analysis, including 1D and 2D NMR, IR, HRESIMS, experimental and calculated electronic circular dichroism (ECD). Notably, this study is the first report on th...

Other studies avoided the use of a zinc salt by generating lithium zincates either by iodine-metal exchange 7 or by deprotonation. 8 In 2002, Gauthier and co-workers documented an approach through lithium zincates using only one third equivalent of zinc chloride for the synthesis of 5-aryl-2-furaldehydes from 5-lithio-2-furaldehyde diethyl acetal. 9 In addition, Mutule and Suma described in 200...