of aryl cyanides with diboron in the presence of a rhodium/Xantphos catalyst and DABCO affords arylboronic esters via carbon-cyano bond cleavage. This unprecedented mode of reactivity for a borylrhodium species allows the regioselective introduction of a boryl group in a late stage of synthesis.
Mechanistic Studies into Amine-Mediated Electrophilic Arene Borylation and Its Application in MIDA Boronate Synthesis
作者:Viktor Bagutski、Alessandro Del Grosso、Josue Ayuso Carrillo、Ian A. Cade、Matthew D. Helm、James R. Lawson、Paul J. Singleton、Sophia A. Solomon、Tommaso Marcelli、Michael J. Ingleson
DOI:10.1021/ja3100963
日期:2013.1.9
computational study, the borylation of activated arenes at 20 °C proceeds through an S(E)Ar mechanism with borenium cations, [Y(2)B(amine)](+), the key electrophiles. For catecholato-borocations, two amine dependent reaction pathways were identified: (i) With [CatB(NEt(3))](+), an additional base is necessary to accomplish rapid borylation by deprotonation of the borylated arenium cation (σ complex), which otherwise
Synthesis of Dibenzo[<i>h</i>,<i>rst</i>]pentaphenes and Dibenzo[<i>fg</i>,<i>qr</i>]pentacenes by the Chemoselective C–O Arylation of Dimethoxyanthraquinones
A convenient method for the syntheses of dibenzo[h,rst]pentaphenes and dibenzo[fg,qr]pentacenes via the ruthenium-catalyzed chemoselective C–O arylation of 1,4- and 1,5-dimethoxyanthraquinones is described. Dimethoxyanthraquinones reacted selectively with arylboronates at the ortho C–O bonds to give diarylation products. An efficient two-step procedure consisting of a Corey–Chaykofsky reaction and
A bicyclo-type cage-shaped compound consisting of three sexithiophenes was successfully synthesized and characterized by NMR, HRMS, and X-ray crystallographic analysis. The strained cage architecture was reflected in the blue-shifted absorption spectrum relative to its linear analogue. Intramolecular interaction between three-dimensionally fixed sexithiophenes was suggested by electrochemical analysis
Fine-Tuning the Nucleophilic Reactivities of Boron Ate Complexes Derived from Aryl and Heteroaryl Boronic Esters
作者:Guillaume Berionni、Artem I. Leonov、Peter Mayer、Armin R. Ofial、Herbert Mayr
DOI:10.1002/anie.201410562
日期:2015.2.23
glycol, neopentyl glycol, catechol), and the counterions on the nucleophilicreactivity of the boronatecomplexes were examined. A Hammett correlation confirmed the polar nature of their reactions with benzhydrylium ions, and the correlation lg k(20 °C)=sN(E+N) was employed to determine the nucleophilicities of the boronatecomplexes and to compare them with those of other borates and boronates. The
衍生自噻吩基和呋喃基硼酸酯和芳基锂化合物的硼酸盐络合物已通过X射线晶体学进行了分离和表征。分析了与碳正离子和亚胺离子反应的产物及其机理。通过UV / Vis光谱监测这些反应的动力学,并检查了芳基取代基,二醇配体(频哪醇,乙二醇,新戊二醇,邻苯二酚)和抗衡离子对硼酸酯络合物的亲核反应性的影响。哈米特(Hammett)相关性证实了它们与苯甲基离子的反应的极性,相关性lg k(20°C)= s N(E + N)用于确定硼酸盐配合物的亲核性,并将其与其他硼酸盐和硼酸盐的亲核性进行比较。发现新戊基和乙二醇衍生物的反应性比频哪醇和邻苯二酚衍生物高10 4倍。