Search results for "stereochemistry"

Electrophilic substitution and cyclization of 2,2′-bis(N-methylindolyl): A simple access to potential protein kinase C inhibitor

1994

A strategy is described for the synthesis of functionalized and cyclized 2,2′-bisindolyl derivatives related to several basic systems of natural products. The starting 2,2′-bis(N-methylindolyl) (8) reacts with a variety of electrophiles and electrophilic dienophiles to furnish the novel, functionalized and cyclized bisindolyl derivatives 9–16. In addition, some reactivity and structural aspects are discussed; an X-ray crystallographic analysis of the 2,2′-bisindolyl 8 provided valuable information for the conformational analyses.

ChemInform Abstract: Reactions of Pyrano(3,4-b)indol-3-ones with Dienophiles: Consecutive (4 + 2) Cycloaddition/Cycloreversion/1,2 Elimination.

1990

Methylpyrano[3,4-b]indol-3-ones 1 react with selected dienophiles (as acetylene equivalents) in a consecutive Diels-Alder/cycloreversion/1,2 elimination reaction sequence to furnish the 1-methyl- and 1,4-dimethylcarbazoles 4.

The use of topological models in analytical chemistry

2005

In the present paper, the possible analytical applications of two toplogical models, the DARC model and the group contribution model, are discussed. Both models are applied to obtain calibration laws, which relate UV and IR characteristics with the chemical structure of ethylene oxide condensates. The group contribution model is also applied to determine the contribution of each part of the different compounds involved in a chemical interaction process, having established the sensitization parameters of benzodiazepines and anionic surfactants from the micellar enhancement fluorescence.

Components of the Sex Pheromone of Chilo Supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal

1995

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.

Understanding the reactivity of captodative ethylenes in polar cycloaddition reactions. A theoretical study

2008

The electrophilic/nucleophilic character of a series of captodative (CD) ethylenes involved in polar cycloaddition reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The transition state structures for the electrophilic/nucleophilic interactions of two CD ethylenes toward a nucleophilically activated ethylene, 2-methylene-1,3-dioxolane, and an electrophilically activated ethylene, 1,1-dicyanoethyelene, have been studied, and their electronic structures have been characterized using both NBO and ELF methods. Analysis of the reactivity indexes of the CD ethylenes explains the reactivity of these species. While the electrophilicity of the molecules accounts for…

ChemInform Abstract: Components of the Sex Pheromone of Chilo supressalis: Efficient Syntheses of (Z)-11-Hexadecenal and (Z)-13-Octadecenal.

2010

Abstract (Z)-11-Hexedecenal 1a and (Z)-13-octadecenenal 2a, components of the sex attractant pheromone of Chilo supressalis, have been synthesized as their ethylene acetals 1b and 2b from cyclododecanone 3, through intermediacy of the C12 ω functionalized acetals 8 and 12.

Jatrophane and tigliane diterpenes from the latex of Euphorbia obtusifolia

1999

The latex of Euphorbia obtusifolia var. obtusifolia yielded twelve new diterpene polyesters. Seven of them displayed the jatrophane framework and five were 4-deoxyphorbol esters. A further isolated tigliane diterpene, a derivative of 4-epi-4-deoxyphorbol, was most likely an artifact of the isolation procedure. All structures were established with the aid of spectroscopic methods.

Developments in the Synthesis of Glycopeptides Containing Glycosyl l-Asparagine, l-Serine, and l-Threonine

1994

ChemInform Abstract: Glycosylation-Induced Asymmetric Synthesis of 1-Substituted Tetrahydroisoquinolines.

2008

2,3,4,5,6-Pentabromophenyl phenyl ether

2002

The title compound, C12H5Br5O, belongs to a group of flame retardants known as polybrominated di­phenyl ethers (PBDE). Salient features of the packing are stabilization due to intermolecular Br⋯Br contacts in the ab plane and aromatic intermolecular contacts along the c direction.