A New Synthesis of<i>o</i>-Quinonemethides and Their Inter- and Intramolecular Cyclization Reactions
作者:Tsutomu Inoue、Seiichi Inoue、Kikumasa Sato
DOI:10.1246/bcsj.63.1062
日期:1990.4
The reaction of o-[1-(alkylthio)alkyl]phenols with silver(I) oxide at room temperature generated o-quinonemethides in good yields along with silver alkanethiolate. This mechanism, based upon one-electron oxidation, is excluded in view of several experimental facts. The resulting o-quinonemethides reacted efficiently with ethyl vinyl ether to afford cis-chromans as the result of endo cycloaddition between (E)-o-quinonemethides and the ether. Similarly, o-[1-(alkylthio)allyl]phenols were converted to cis-chromans via the corresponding (E)-o-quinonemethides (6-allylidenecyclohexadienone). In the absence of dienophiles, some chromenes were obtained from the allylphenols.
A Mild Ligand-Free Iron-Catalyzed Liberation of Alcohols from Allylcarbonates
作者:André P. Dieskau、Bernd Plietker
DOI:10.1021/ol202270g
日期:2011.10.21
from most carbonates the allyloxy carbonyl protecting groupcan be cleavedunderneutralconditions using metal catalysis. However, most of the catalysts employed to date are based upon precious metals. Herein we present two protocols for the mild Fe-catalyzed liberation of alcohols from allylcarbonates that are characterized by broad functional group tolerance and exclusive chemoselectivity.
Acid-catalyzed hydrolysis of alkyl vinyl and propenyl sulfides
作者:T. Okuyama、M. Nakada、T. Fueno
DOI:10.1016/0040-4020(76)85140-x
日期:1976.1
ethyl, isopropyl, and t-butyle vinyl sulfides have been measured in 10% aqueous acetonitrile. It was found that their reactivities decrease in this order. General acid catalysis was observed. The rate was smaller in a deuterium medium (kD2O/kH2O = 0.34). The deuterium exchange between sulfide and solvent was not detected during hydrolysis. Some propenylsulfides have also been studied, their cis isomers
已在10%乙腈水溶液中测量了甲基,乙基,异丙基和叔丁基乙烯基硫化物的酸催化水解速率。发现它们的反应性按此顺序降低。观察到一般的酸催化。在氘代介质中的比率较小(k D 2 O / k H 2 O = 0.34)。水解过程中未检测到硫化物与溶剂之间的氘交换。还研究了一些丙烯基硫化物,它们的顺式异构体比不涉及几何异构化的反式对应物更具反应性。讨论了反应机理和取代基对反应性的影响。
Ruthenium–porphyrin-catalyzed carbenoid addition to allylic compounds: application to [2,3]-sigmatropic rearrangements of ylides
The catalytic effectiveness of ruthenium porphyrins for ylide generation in reactions of ethyl diazoacetate and diisopropyl diazomethylphosphonate with allylic amines, sulfides and iodides is described for the first time. These reactions result mainly in products of the [2,3]-sigmatropicrearrangement of intermediate allylic ylides.
R3SiMgMe and MnCl2 are disclosed. (1) The manganese species reacted with terminal acetylenes to give 1,2-disilylated 1-alkenes. Mono- and bis(trimethylsilyl) acetylenes gave tri- and tetrasilylated ethenes, respectively, in good yields. Highly strained tetrakis(trimethylsilyl) ethene has now become easily accessible by this technique. (2) The reaction of alkenyl halides, alkenyl sulfides, and enol phosphates