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
Stereoselective Synthesis of (<i>E</i>)-5-Hydroxy-4-methyl-2-alkenoates by Palladium-Catalyzed Stereospecific Hydrogenolysis of (<i>E</i>)-4,5-Epoxy-4-methyl-2-alkenoates with Ammonium Formate
Palladium-catalyzedhydrogenolysis of (E)-4,5-epoxy-4-methyl-2-alkenoates with HCO2H-Et3N gave (E)-5-hydroxy-4-methyl-2-alkenoates in good yields with inversion of stereochemistry.
Cooperative Catalysis of Samarium Diiodide and Mercaptan in a Stereoselective One-Pot Transformation of 5-Oxopentanals into δ-Lactones
作者:Jue-Liang Hsu、Chao-Tsen Chen、Jim-Min Fang
DOI:10.1021/ol9911526
日期:1999.12.1
[GRAPHICS]We demonstrate a general method for conversion of various 5-oxopentanals to substituted delta-lactones and 1-oxa-2-decalones by the synergistic catalysis of samarium diiodide and 2-propanethiol (or disulfide), The deliberate use of mercaptan is advantageous to facilitate the catalytic cycle, This method shows high stereoselectivities, and an enantioselective procedure is feasible by using the chiral mercaptan (1R,2S)-1 phenyl-2-(N-acetamido)propanethiol as a promoter.
Palladium-catalyzed selective hydrogenolysis of alkenyloxiranes with formic acid. Stereoselectivity and synthetic utility