A one-pot procedure involving radical conjugate addition of B-alkylcatecholboranes to enones followed by intramolecular aldol reaction is reported. Application to the stereoselective synthesis of monocyclic and bicyclic products with up to four contiguous stereogenic centers is presented.
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
Grubbs Metathesis Enabled by a Light‐Driven
<i>gem</i>
‐Hydrogenation of Internal Alkynes
作者:Tobias Biberger、Raphael J. Zachmann、Alois Fürstner
DOI:10.1002/anie.202007030
日期:2020.10.12
complexes instigate a light‐drivengem‐hydrogenation of internal alkynes with concomitant formation of discrete Grubbs‐type ruthenium carbene species. This unorthodox reactivity mode is harnessed in the form of a “hydrogenative metathesis” reaction, which converts an enyne substrate into a cyclic alkene. The intervention of ruthenium carbenes formed in the actual gem‐hydrogenation step was proven by the
作者:Zhao Chen、Jinhua Liang、Jun Yin、Guang-Ao Yu、Sheng Hua Liu
DOI:10.1016/j.tetlet.2013.08.049
日期:2013.10
A novel intermolecular Alder-enereaction based on aryne and olefins was developed. We performed this transformation under mild conditions such as at room temperature, and this reaction displayed high selectivity and good yields only in the presence of CsF. Hence, the intermolecular Alder-enereaction of aryne with olefins provides an effective route to synthesize derivatives of olefins.
Convenient ‘one-flask’ synthesis of olefins. Reaction of α-chloroketones with Grignard reagents and lithium
作者:José Barluenga、Miguel Yus、Pablo Bernad
DOI:10.1039/c3978000847a
日期:——
Olefins and diolefins with the double bonds in predetermined positions are prepared in a one-step process in moderate to good yields by the reaction of α-chloroketones with Grignardreagents and then with lithium.