Superacid-Catalyzed Reactions of Cinnamic Acids and the Role of Superelectrophiles<sup>1</sup>
作者:Rendy、Yun Zhang、Aaron McElrea、Alma Gomez、Douglas A. Klumpp
DOI:10.1021/jo030327t
日期:2004.4.1
formation of dicationic intermediates (superelectrophiles), and the reactions can lead to either chalcone-type products or indanone products. The directobservation of a dicationic species (by low-temperature 13C NMR) is reported. We provide clear evidence that protonated carboxylic acid groups (or the corresponding acyl cation) can enhance the reactivity of an adjacent electrophilic center. Triflic acid
已经研究了肉桂酸和相关化合物的化学性质。在超酸催化的芳烃反应中,提出了两种相互竞争的反应机理。两种机理都涉及形成阳离子型中间体(超亲电子试剂),并且这些反应可导致查尔酮类产物或茚满酮产物。据报道直接观察到一种特殊的物质(通过低温13 C NMR)。我们提供了明确的证据,表明质子化的羧酸基团(或相应的酰基阳离子)可以增强相邻亲电中心的反应活性。三氟甲磺酸还被发现是从肉桂酸直接合成某些缺电子的查耳酮和杂环查耳酮的有效酸催化剂。
Oxidative Transformation of <i>tert</i>-Cyclobutanols by Palladium Catalysis under Oxygen Atmosphere
作者:Takahiro Nishimura、Kouichi Ohe、Sakae Uemura
DOI:10.1021/jo0016475
日期:2001.2.1
Palladium(II)-catalyzed oxidative reaction of tert-cyclobutanols involving the cleavage of a C-C bond via beta-carbon elimination under atmospheric pressure of oxygen is described. An alkylpalladium intermediate produced by beta-carbon elimination from a Pd(II) alcoholate gives a variety of products, depending on the substituents on the cyclobutane ring, in which reactions such as dehydrogenative ring
The intramolecular carbocyclization of tethered alkynylketones to five-membered cyclic enones is shown to be catalyzed by trifluoromethanesulfonic acid in MeOH, proceeding in good to excellent yields and with high selectivities.
Combined use of Tf2NH and In(OTf)3 effectively promotes the cyclization of alk-5-ynyl ketones to cyclopent-1-enyl ketones at 30 °C. Single use of Tf2NH or In(OTf)3 requires heating at 50 °C for efficient cyclization. The In(OTf)3-promoted reaction of certain alk-5-ynyl ketones gives cyclohept-2-enones mainly.