Column and thin-layer chromatographic systems employing silver nitrate-impregnated adsorbents are described for the separation of sterol acetates which differ in the number of double bonds in the steroid nucleus or side chain.

The electroreduction of aryl halides (bromides or chlorides) allows the coupling reaction with vinylic acetates, in the presence of 2,2-bipyridine and catalytic amounts of cobalt bromide, leading to styrene derivatives in good yields. q 2003 Elsevier Science Ltd. All rights reserved.

Benzylic acetates reacted with arylboronic acids in the presence of a DPEphos-[Pd(eta3-C3H5)Cl]2 catalyst when tert-amyl alcohol was used as a solvent, and the catalytic cross-couplings produced diarylmethanes in high yields (up to 94% isolated yield).

The aand /?-methyl glycosides (IV and V, respectively) of the antibiotic streptozotocin (I) have been synthesized. In addition, analogs involving epimeric changes at C2 (III) and C4 (II), and of two Q analogs, 3-/?-Dglucopyranosyl-1-methyl-l-nitrosourea (XXIII) and the corresponding Dgalactopyranosyl compound (XXV), together with their tetra-O-acetates (XXII and XXIV, respectively) have been pr...

Pd-catalyzed asymmetric allylic sulfonation of di-aryl-substituted allylic acetates with sodium sulfite (Na2SO3) in THF-H2O at room temperature was described. This method directly provided allylic sulfonic acids in up to excellent yield and enantioselectivity.

The efficient synthesis of functionalized enamines including β-enaminoesters was effectively accomplished by the direct condensation of functionalized sp(3) carbanions such as acetates with formamides using in situ generated HMDS base from catalytic cesium fluoride and stoichiometric tristrimethylsilylamine.

Controlling nanocomposite composition and morphology is a vital step toward designing new and advanced materials. The current work presents the results of an experimental investigation of the use of mixed-phase reactants for the synthesis of nanocomposite materials. Gas-phase tetramethyltin was used as a precursor for tin dioxide (SnO2). Metal additives were introduced to the SnO2 synthesis sys...

Asymmetric coupling proceeds efficiently between propargylic acetates, cycloalkenes and electron-rich heteroarenes including indoles, pyrroles, activated furans thiophenes. 2,3-Disubstituted tetrahydrofurans pyrrolidines are produced in trans configuration excellent enantiomeric ratios. The reaction via Wacker-type attack of nucleophilic on alkenes by allenyl PdII species.