Tetrapropylammonium Perruthenate Catalyzed Glycol Cleavage to Carboxylic (Di)Acids
摘要:
A new method to accomplish glycol cleavage to carboxylic (di)acids in one step using catalytic amounts of tetrapropylammonium perruthenate (TPAP) together with N-methylmorpholine N-Oxide (NMO) as the stoichiometric oxidant is presented. In addition to regenerating the active catalyst, the N-oxide stabilizes intermediary carbonyl hydrates and thereby shifts a crucial equilibrium. The mild oxidation protocol is applicable to a broad range of substrates providing the respective acids, diacids, or keto acids in high yields.
Catalytic Intermolecular Coupling of Rhodacyclopentanones with Alcohols Enabled by Dual Directing Strategy
作者:Ya-Lin Zhang、Rui-Ting Guo、Jia-Hao He、Xiao-Chen Wang
DOI:10.1021/acs.orglett.9b01420
日期:2019.6.7
A catalytic carbonylative ring-opening and functionalization reaction of poorly activated cyclopropanes has been developed. The key achievement of this work is the accomplishment of an unprecedented effective intermolecular trapping of the rhodacyclopentanone intermediate, which is derived from rhodium-mediated carbonylative insertion of poorly activated cyclopropanes, by an external reactant. The
Homogeneous cis-dihydroxylation and epoxidation of olefins with high H2O2 efficiency by mixed manganese/activated carbonyl catalyst system
作者:Jelle Brinksma、Lizette Schmieder、Gerbert van Vliet、Rob Boaron、Ronald Hage、Dirk E De Vos、Paul L Alsters、Ben L Feringa
DOI:10.1016/s0040-4039(02)00292-7
日期:2002.4
[Mn2O3(tmtacn)2](PF6)2 (tmtacn=1,4,7-trimethyl-1,4,7-triazacyclononane) in combination with glyoxylic acid methylester methyl hemiacetal (GMHA) results in a highly active and hydrogenperoxideefficientcatalyst for the epoxidation of olefins as well as the first homogeneous catalytic cis-dihydroxylation system with H2O2 and with turnover numbers up to 420.
[Mn 2 O 3(tmtacn)2 ](PF 6)2(tmtacn = 1,4,7-三甲基-1,4,7-三氮杂环壬烷)与乙醛酸甲酯甲基半缩醛(GMHA)结合使用会导致一种高活性和过氧化氢有效的催化剂,用于烯烃的环氧化,以及第一个均相催化的H 2 O 2顺式-二羟基化系统,其周转数最高为420。
A facile synthesis of vicinal cis-diols from olefins catalyzed by in situ generated Mn<sub>x</sub>O<sub>y</sub> nanoaggregates
作者:Diğdem Dalmizrak、Haydar Göksu、Mehmet Serdar Gültekin
DOI:10.1039/c5ra01646k
日期:——
The MnxOy oxide derivatives, mainly Mn3O4 nanoaggregates, were generated in situ by KMnO4/H2O2 during the synthesis of vicinal cis-diols from olefins.
from the results observed with strained and sterically hindered syn 1,2-diols, which undergo oxidative cleavage via a 12-I-5 spirobicyclic periodinane. The use of TFA, a protonating solvent, promotes the formation of the 12-I-5 intermediate for 1,2-diols of all types (sec,sec, sec,tert and tert,tert), leading to efficient oxidative fragmentation.
Stability of boronic esters – Structural effects on the relative rates of transesterification of 2-(phenyl)-1,3,2-dioxaborolane
作者:Chandra D. Roy、Herbert C. Brown
DOI:10.1016/j.jorganchem.2006.10.013
日期:2007.1
phenylboronic ester 2-(phenyl)-1,3,2-dioxaborolane with a wide variety of structurally modified diols, have been studied to understand the factors influencing the relative stabilities of boronic esters. It is found that the alkyl substituents on the α-carbons of diols slow down the transesterification, but produce thermodynamically more stable boronic ester. Six-membered boronic esters are thermodynamically
已研究了非手性环状苯基硼酸酯2-(苯基)-1,3,2-二氧杂硼烷与各种结构改性的二醇的相对反应速率,以了解影响硼酸酯相对稳定性的因素。发现二醇的α-碳上的烷基取代基减慢了酯交换反应,但是产生了热力学上更稳定的硼酸酯。六元硼酸酯在热力学上比其相应的五元类似物稳定。在环状1,2-二醇中,顺式-1,2-环戊二醇可瞬间取代乙二醇,而反式-1,2-环戊二醇则完全不活泼,这表明顺式1,2-二醇的-立体化学是酯交换的先决条件。在1,5-二醇中,二乙醇胺相当快地取代了乙二醇,形成了更稳定的双环螯合物,其中氮通过配位键连接到硼上(如11 B NMR光谱所证明的)。二(乙二醇)的氧原子和2,2'-硫代二乙醇的硫原子无助于从其硼酸酯中置换乙二醇。