Enantioselective α-Vinylation of Aldehydes via the Synergistic Combination of Copper and Amine Catalysis
摘要:
The enantioselective alpha-vinylation of aldehydes using vinyl iodonium triflate salts has been accomplished via the synergistic combination of copper and chiral amine catalysis. These mild catalytic conditions provide a direct route for the enantioselective construction of enolizable alpha-formyl vinylic stereocenters without racemization or olefin transposition. These high-value coupling adducts are readily converted into a variety of useful olefin synthons.
α-Vinylation of 1,3-Dicarbonyl Compounds with Alkenyl(aryl)iodonium Tetrafluoroborates: Effects of Substituents on the Aromatic Ring and of Radical Inhibitors
1,3-dicarbonyl compounds with 4-tert-butyl-1-cyclohexenyl(aryl)iodonium 2 and 1-cyclopentenyl(aryl)iodonium tetrafluoroborates 3 are reported. Frequently, alpha-phenylations compete with the vinylations in the reaction of 1,3-dicarbonyl compounds with alkenyl(phenyl)iodoniumsalts 2a and 3a. Use of alkenyl(p-methoxyphenyl)iodoniumsalts 2b and 3b, however, leads to selective alpha-vinylation at the
One-Pot Synthesis of α-Trimethylsilyl Enones from Vinylsilanes
作者:Waldemar Adam、Markus J. Richter
DOI:10.1055/s-1994-25433
日期:——
Photooxygenation of vinylsilanes in the presence of acetic anhydride and pyridine afforded α-trimethylsilyl enones 1 in moderate to good yields. Since the required starting materials are readily available, the present approach constitutes a useful alternative to existing methods for the preparation of α-trimethylsilyl enones 1.
1,2,3-cyclohexatriene and cyclohexen-3-yne: two new highly strained C6H6 isomers
作者:William C. Shakespeare、Richard P. Johnson
DOI:10.1021/ja00179a050
日期:1990.11
La reaction de trifluoromethanesulfonate de 6-trimethylilylcyclohexa-1,5-dienyle avec le CsF dans le DMSO donne le cyclohexa-1,2,3-triene qui est piege par le diphenylbenzo[c]furane et fournit l'adduit correspondant. Le cyclohex-1-en-3-yne est synthetise a partir de 2-bromocyclohexa-1,3-dienyl trimethyl silane et est piege de la meme maniere
La 反应 de trifluoromethanesulfonate de 6-trimethyllyylylcyclohexa-1,5-dinyle avec le CsF dans le DMSO donne le cyclohexa-1,2,3-triene qui est piege par le diphenylbenzo[c]furane etfournit l'adduit 通讯员。Le cyclohex-1-en-3-yne est 合成 a partir de 2-bromocyclohexa-1,3-dienyl trimethyl 硅烷 et est piege de la meme maniere
Highly stereocontrolled synthesis of [3.3.3] propellane sesquiterpenes. ( ± )-Modhephene and (±)-epimodhephene
作者:Heinrich Schostarez、Leo A. Paquette
DOI:10.1016/0040-4020(81)80009-9
日期:1981.1
Stereospecific totalsynthesis of (±)-modhephene (2) and (±)-epimodhephene (3) are reported. Conjugate addition of 1-trimethylsilyl-1-butyn-4-yl cuprate (BF3-etherate catalysis) to bicyclic ketone 6, fluoride ion-promoted deblocking of the terminal acetylene, and ene reaction, gave tricyclic enone 11. Sequential Wittig methylenation, regiocontrolled epoxidation, and Lewis acid catalyzed isomerization
Chromium(II)-Mediated Reactions of Iodonium Tetrafluoroborates with Aldehydes: Umpolung of Reactivity of Diaryl-, Alkenyl(aryl)-, and Alkynyl(aryl)iodonium Tetrafluoroborates
作者:Da-Wei Chen、Masahito Ochiai
DOI:10.1021/jo990809y
日期:1999.9.1
of iodonium salts with anhydrous chromium dichloride, followed by their nucleophilic addition to aldehydes to yield alcohols. In contrast to the reaction of aryl and alkenyl halides with chromium dichloride, these iodonium salts are so active that organochromium(III) could be generated without using a nickel catalyst. Substituent effects of unsymmetrically substituteddiaryliodoniumsalts on the product