نتایج جستجو برای: stereoselective

تعداد نتایج: 4707  

Journal: :Canadian Journal of Chemistry 1993

Journal: :Synthesis 2021

Abstract In this paper, the synthesis of carbon skeleton cotylenin A aglycone is described. The key reactions, including an intramolecular aldol reaction, coupling and a ring-closing meta­thesis, allow for effective stereoselective access to aglycone. stereochemistry was confirmed by single-crystal X-ray crystallographic analyses related compounds.

Journal: :Chemical communications 2011
Jonas F Buergler Antonio Togni

Intramolecular nucleophilic substitution of a trifluoromethyl group to form a 1,2-diphosphole derivative followed by the sequential addition of an alkylating agent and a carbanion are the key steps in the stereoselective synthesis of novel ferrocenyl diphosphines for asymmetric catalysis.

Journal: :Organic & biomolecular chemistry 2007
Changhong Ko Richard P Hsung

An unexpected stereoselective anomeric substitution with carbamates promoted by HNTf2 is described here. Our experiments suggest that the observed diastereoselectivity is a result of thermodynamic equilibration of protonated N-acyl aminals.

Journal: :Journal of natural products 2003
Veronica Armstrong Alejandro F Barrero Enrique J Alvarez-Manzaneda Manuel Cortés Beatriz Sepúlveda

An efficient and highly stereoselective synthesis of cytotoxic 8-epipuupehedione (1b) was achieved starting from natural (-)-drimenol (6). The key step to obtain stereoselectivity was the simultaneous demethylation and oxidation of the dihydrobenzopyran methoxy derivatives 10a and 10b.

Journal: :Organic & biomolecular chemistry 2007
David L Waller Corey R J Stephenson Peter Wipf

Oxidative rearrangement of cyclic enol ethers leads to alpha-alkoxyesters. In the presence of a neighboring spiroether, this approach provides a stereoselective access to spiroketals. A modified proposal for the biosynthesis of acutumine is presented.

Journal: :Chemical communications 2010
Pinhong Chen Lidong Cao Wenhai Tian Xinfeng Wang Chaozhong Li

The first asymmetric synthesis of indole alkaloid (+)-subincanadine F was successfully accomplished with the uncommon 7-endo-trig stereoselective radical cyclization as the key step and its absolute configuration was thus assigned.

Journal: :Chemical communications 2015
Siyu Guo Peng Yang Jianrong Steve Zhou

Asymmetric transfer hydrogenation of electron-deficient olefins is realized with nickel catalysts supported by strongly σ-donating bisphosphines. Deuterium labeling experiments point to a reaction sequence of formate decarboxylation, asymmetric hydride insertion and non-stereoselective protonation of resulting nickel enolates.

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