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A study was conducted to determine if five- and six-membered-ring heterocycles and carbocycles can be efficiently formed by the regio- and stereoselective reaction between allenes and vinylic halides. These halides feature amine, alcohol, amide, carboxylic acid, sulfonamide and carbanion-stabilizing groups. Results confirm the effectiveness of the synthesizing approach.

A study used the treatment of o-iodo- or o-bromobenzaldehyde with many internal alkynes in the presence of a palladium catalyst, to prepare in responsible to high yields, several 2,3-disubstituted 1-indenones. Synthetically, the technique offers a particularly easy pathway to stable impeded indenones consisting of aryl, silyl and tert-alkyl groups. Sterical regulation of the regiochemistry of this reaction, and the direction of the reaction through a palladium-(IV) intermediate, have been identified.

Arylpalladium formation and addition to the diene, palladium formation and intramolecular pi-allylpalladium displacement were part of a mechanism used to obtain monocyclic and bicyclic 6-membered ring heterocycles and carbocycles in high yields from the palladium-catalyzed annulation of 1, 4-dienes by aryl halides bearing ortho-heteroatoms and carbanion-stabilizing groups. Ether and saturated aqueous NH4Cl were used to work up the reaction mixture obtained by heating under N2 for the required period, the aryl halide, the base, palladium acetate, n-Bu4NCl, the 1,4-diene, DMF and 5 mol % of PPh3.

A highly useful new synthetic route to 2,3-disubstituted indoles is presented. With palladium as catalyst, 2-iodoaniline and the corresponding N-methyl-, -acetyl, and -tosyl derivatives were coupled with a wide range of internal alkynes to obtain 2,3-disubstituted indoles in good to excellent yields. The utilization of an excess of the alkyne and a sodium or potassium acetate or carbonate base plus 1 equiv of either LiCl or n-Bu4NCl yields the best results.

The enantioselectivity of native and derivatized cyclodextrin stationary phases and macrocyclic glycopeptides for chiral pterocarpans was evaluated using high performance liquid chromatography (HPLC). All enantiomers could be baseline resolved in the reverse phase mode on cyclodextrin-based Cyclobond chiral stationary phases (CSPs). The hydroxypropyl-β-cyclodextrin, acetyl-β-cyclodextrin, and gamma-cyclodextrin CSPs show the broadest enantioselectivity in the reverse phase mode. Some compounds were baseline separated on the ristocetin A and vancomycin macrocyclic glycopeptide chiral stationary phases in the reverse phase mode. Separations on the ristocetin A columns produced the highest resolutions (up to ∼7.1) in this study. The 3,5-dimethylphenyl carbamate derivatized cyclodextrin column showed the broadest enantioselectivity in normal phase LC. Of the macrocyclic glycopeptide CSPs, ristocetin A and teicoplanin aglycone (Chirobiotic R and TAG, respectively) showed enantioselectivity for the most compounds in the normal phase mode. However, baseline separations were only achieved with the teicoplanin and teicoplanin aglycone. [ABSTRACT FROM AUTHOR]