bis-pinacol ester of 2,2'-biphenyl diboronic acid;bis-pinacol ester of biphenyl-2,2'-diboronic acid;(pinacolato)BC6H4C6H4B(pinacolato);pinBC6H4C6H4Bpin;4,4,5,5-tetramethyl-2-[2-[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]phenyl]-1,3,2-dioxaborolane
A Suzuki Coupling Based Route to 2,2‘-Bis(2-indenyl)biphenyl Derivatives
摘要:
Because of the promising performance in olefin polymerization of 2,2'-bis(2-indenyldiyl)biphenyl zirconium dichloride, we developed a new and broadly applicable route to 2,2'-bis(2-indenyl)biphenyl derivatives. Reaction of the known 2,2'-diiodobiphenyl (26) with the new 2-indenyl boronic acid (23) did not result in the desired 2,2'-bis(2-indenyl)biphenyl (10); instead an isomer thereof, (spiro-1,1-(2,2'-biphenyl)-2-(2-indenyl)indane) (27), was obtained. It was found that compound 10 could be made via a palladium-catalyzed reaction of 2,2-biphenyldiboronic acid (31) with 2-bromoindene (21) under standard Suzuki reaction conditions. However, the yield of this reaction was low at low palladium catalyst loadings, due to a competitive hydrolysis reaction of 2,2-biphenyldiboronic acid (31). HTE techniques were used to find an economically viable protocol. Thus, use of the commercially available 1.0 molar solution of (n-BU)(4)NOH in methanol with cosolvent toluene led to precipitation of the pure product in a fast and clean reaction, using only 0.7 mol % (0.35 mol % per C-C) of the expensive palladium catalyst.
献给教授迪特尔·恩德斯博士在他的70之际个生日。 抽象的 具有刚性构象的羟基四亚苯基是在不对称合成中用作手性配体的潜在候选者。发现醛与重氮-N,N-二甲基乙酰胺之间的高度非对映选择性和对映选择性Darzens反应是由由Ti(O i Pr)4和手性1,16-二羟基四亚苯基原位形成的手性钛络合物催化的,从而导致形成中等至高收率的顺式-缩水甘油酰胺,具有出色的对映体纯度(40–99%收率,高达99%ee)。 具有刚性构象的羟基四亚苯基是在不对称合成中用作手性配体的潜在候选者。发现醛与重氮-N,N-二甲基乙酰胺之间的高度非对映选择性和对映选择性Darzens反应是由由Ti(O i Pr)4和手性1,16-二羟基四亚苯基原位形成的手性钛络合物催化的,从而导致形成中等至高收率的顺式-缩水甘油酰胺,具有出色的对映体纯度(40–99%收率,高达99%ee)。
The dimethyl sulfide adduct 2(DMS) is a crystalline storage form of the unstable hydroboration reagent 9-H-9-borafluorene (2); 2(DMS) is available by the addition of DMS to either in situ generated [2]2 or 1,2-(2,2′-biphenylylene)diborane(6) (7).
Breaking Bonds and Forming Nanographene Diradicals with Pressure
作者:Maude Desroches、Paula Mayorga Burrezo、Joël Boismenu-Lavoie、Miriam Peña Álvarez、Carlos J. Gómez-García、Jon M. Matxain、David Casanova、Jean-François Morin、Juan Casado
DOI:10.1002/anie.201708740
日期:2017.12.18
a closed‐shell butterfly‐shaped structure in the ground state, a curved‐to‐planar fluxional inversion is accessible with a low energy barrier through a biradicaloid transition state. Inversion is primarily driven by the release of strain associated with steric hindrance at the peri position of the anthanthrone core; a low‐lying diradical state is accessible through planarization of the core, which is
制备了新的基于蒽醌的多环支架,该支架具有周围拥挤的醌二甲烷。虽然这些化合物在基态下采用闭壳蝶形结构,但可以通过双自由基过渡态以低能垒实现曲面到平面的通量反演。倒置主要由与周围位阻相关的应变的释放驱动蒽酮芯的位置;通过核心的平面化可以达到低洼的双自由基状态,这是在中等温度下在溶液中实现的。这种转变的最重要方面是,通过在固态下施加适度的压力也可以实现平面化,其中双自由基保持被动力学捕获。从量子化学,补充信息1 H NMR,和拉曼光谱,与磁性实验一起,是用纳米石墨烯状结构具有在局部基团中心的形成一致的外-anthanthrone碳轴承苯基的取代基。
realized in one step. The subtle differences in molecularstructure were confirmed by X-raycrystallography. The mechanisms for the control of different products, which involve a ring-expansion rearrangement, Scholl reactions, and/or Mallory cyclization were proposed on the basis of control experiments and DFT calculations. Such development adds good structure versatility and materials accessibility to