Perchloric Acid-Catalyzed Synthesis of 9-Aryl Xanthenes-9<i>H</i>-3,6-diol and 1,3,6,8-Tetraol in Water
作者:Nikhil Vidyasagar、Rabindra Nanda、Rajesh Mangal、Muthu K. Kathiravan
DOI:10.1080/00397911.2011.578326
日期:2012.11
Abstract Efficient syntheses of xanthenes have been described using a catalytic amount of perchloricacid in water. The high temperature and lengthy reaction time normally required for formation of xanthenes derivatives are not necessary when using a catalytic amount of perchloricacid. The method is relatively inexpensive, easily available, nonvolatile, nonexplosive, and thermally robust to catalyze the
β-boron-functionalized α-aryl carboxylic acids with up to 87% yield and 97% ee under mild conditions. Importantly, α-substituted arylalkenes could also be subject to this protocol with excellent enantiopurities, thereby rendering an efficient approach for the generation of enantioenriched carboxylic acids with an α-chiral all-carbonquaternary center. Moreover, high functional group tolerance, scalable synthesis, and
用CO 2 (一种丰富且可持续的单碳结构单元)对容易获得的烯烃进行催化不对称羧化,可以以原子和步骤经济的方式获得增值的α-立体羧酸,这是非常有吸引力的。然而,这对于合成界来说仍然是一个巨大的挑战。在此,描述了在 CO 2大气压下,铜催化的各种芳基烯烃与二硼的高度区域和对映选择性硼羧化反应的第一个例子,该反应提供了多种手性 β-硼官能化的 α-芳基羧酸,在温和条件下收率 87%,ee 97%。重要的是,α-取代的芳基烯烃也可以采用该方案,具有优异的对映体纯度,从而提供一种有效的方法来生成具有 α-手性全碳四元中心的对映体富集的羧酸。此外,高官能团耐受性、可扩展的合成以及易于获得生物活性化合物,如(-)-东莨菪碱、(-)-山莨菪碱和(-)-托吡卡胺,进一步证明了该策略的合成效用。
Distal<i>p</i>-benzylic deuteration<i>via</i>N-heterocyclic carbene catalyzed ring opening of<i>p</i>-cyclopropylbenzaldehydes
作者:Ye Qiu、Lei Dai、Zhong-Hua Gao、Song Ye
DOI:10.1039/d3ob00394a
日期:——
Deuterium incorporation at selective sites of organic compounds has long attracted the interest of the pharmaceutical industry. Here, we present a distal p-benzylic deuteration via N-heterocyclic carbene catalyzed ring-opening of cyclopropylbenzaldehydes with MeOD as the deuterium source. The corresponding 4-alkylbenzoates with high deuterium incorporation at the benzylic position were obtained in