Stereoselective Synthesis of δ-Lactones from 5-Oxoalkanals via One-Pot Sequential Acetalization, Tishchenko Reaction, and Lactonization by Cooperative Catalysis of Samarium Ion and Mercaptan
作者:Jue-Liang Hsu、Jim-Min Fang
DOI:10.1021/jo016058t
日期:2001.12.1
sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reaction mechanism and stereochemistry are proposed and supported by some experimental evidence. Such samarium ion/mercaptan cocatalyzed reactions show the feature of remote control, which is applicable to the asymmetric synthesis
Unconventional type of allylation reaction at the β-position of ketone carbonyl has been developed based on the β-metallo ketone strategy: treatment of siloxycyclopropanes 1 with allylic chlorides 2 in the presence of silver fluoride results in the effective formation of δ, ε-unsaturated ketones 4.
<i>N</i>-phenyl-substituted pyrrolidines, piperidines and azabicyclics by a tandem reduction-double reductive amination reaction
作者:Richard A. Bunce、Derrick M. Herron、Jason R. Lewis、Sharadsrikar V. Kotturi
DOI:10.1002/jhet.5570400115
日期:2003.1
formed in high yield and are easily purified. The method has also been extended to the synthesis of fused N-phenylazabicyclics from 2-(3-oxo-propyl)cycloalkanones. A high degree of diastereoselectivity for the trans-fused product is observed in substrates having an ester group α to the cycloalkanone carbonyl. Bicyclic precursors lacking this ester group give mixtures of cis and trans products. Finally
A Conjugate Addition of Allylsilanes to α,β-Unsaturated Ketones Catalyzed by Trityl Perchlorate
作者:Masaji Hayashi、Teruaki Mukaiyama
DOI:10.1246/cl.1987.289
日期:1987.2.5
A conjugateaddition of allylsilanes to α,β-unsaturatedketones was effectively promoted by a catalytic amount of trityl perchlorate to give the corresponding Michael adducts in good yields.
Stereochemical Investigations of Samarium(II) Iodide-Promoted 5-Exo and 6-Exo Ketyl-Olefin Radical Cyclization Reactions
作者:Gary A. Molander、Jeffrey A. McKie
DOI:10.1021/jo00109a018
日期:1995.2
Samarium(II) iodide (SmI2)-promoted ketyl cyclizations of several substituted, unsaturated ketones, providing various cyclopentyl and cyclohexyl systems, have been investigated. The resulting experiments provide stereochemical insight into these reactions and in addition outline the synthetic potential of these 5-exe and 6-exo radical cyclization processes.