55738-55-1Relevant academic research and scientific papers
Visible-Light-Promoted Metal-Free Synthesis of (Hetero)Aromatic Nitriles from C(sp3)?H Bonds**
Murugesan, Kathiravan,Donabauer, Karsten,K?nig, Burkhard
, p. 2439 - 2445 (2021)
The metal-free activation of C(sp3)?H bonds to value-added products is of paramount importance in organic synthesis. We report the use of the commercially available organic dye 2,4,6-triphenylpyrylium tetrafluoroborate (TPP) for the conversion of methylarenes to the corresponding aryl nitriles via a photocatalytic process. Applying this methodology, a variety of cyanobenzenes have been synthesized in good to excellent yield under metal- and cyanide-free conditions. We demonstrate the scope of the method with over 50 examples including late-stage functionalization of drug molecules (celecoxib) and complex structures such as l-menthol, amino acids, and cholesterol derivatives. Furthermore, the presented synthetic protocol is applicable for gram-scale reactions. In addition to methylarenes, selected examples for the cyanation of aldehydes, alcohols and oximes are demonstrated as well. Detailed mechanistic investigations have been carried out using time-resolved luminescence quenching studies, control experiments, and NMR spectroscopy as well as kinetic studies, all supporting the proposed catalytic cycle.
Organic electrosynthesis using toluates as simple and versatile radical precursors
Lam, Kevin,Marko, Istvan E.
supporting information; experimental part, p. 95 - 97 (2009/03/11)
The electrolysis of toluate esters leads smoothly to the formation of the radical of the alkyl fragment. This property has been used to develop a new electrochemical deoxygenation reaction. The Royal Society of Chemistry.
Toluates: unexpectedly versatile reagents
Lam, Kevin,Markó, István E.
experimental part, p. 10930 - 10940 (2010/02/28)
The mechanism of the monoelectronic reduction of aromatic esters has been investigated. The unexpected synthetic utility of the toluate moiety in the deoxygenation of alcohols and the allylation of ketones is also reported. Finally, the use of aromatic esters as robust, though easily removable, protecting groups is depicted.
Organic reactions in liquid crystalline solvents. 1. The thermal cis-trans isomerization of a bulky olefin in cholesteric liquid crystalline solvents
Leigh, William J.,Frendo, Debbie T.,Klawunn, Paul J.
, p. 2131 - 2138 (2007/10/02)
The effect of cholesteric liquid crystalline solvents on the energetics of rotational thermal cis-trans isomerization of olefins has been examined.Rate constants have been obtained over a 70-degree temperature range for isomerization of trans-1,2-di-(4-cyanophenyl)-1,2-diphenyl-ethylene in two isotropic solvents and three cholesteric liquid crystals and the Arrhenius parameters determined.The rates of isomerization are found to be consistently slower in the liquid crystalline phases compared to the isotropic solvents.The Arrhenius parameters for isomerization of the olefin in the isotropic solvents (Ea = 34.8 +/- 0.3 kcal/mol; ΔS+ = - 1.5 +/- 0.5 e.u.) compare favourably with reported values for its isomerization in benzene solution.In the cholesteric phases, Ea is consistently 1-1.5 kcal/mol higher and ΔS+ slightly more positive than the corresponding values for the isotropic solvents.The results are tentatively rationalized in terms of disruption of liquid crystalline orders as the olefin twists from its pseudo-planar, ground state geometry through the globular, twisted transition state.The magnitude of this effect is proposed to depend on both the difference in steric bulk of the ground and transition states and the "tightness" of the solvation shell seen by the isomerizing molecule.It is believed that in the present case the observed effects are somewhat truncated as a result of rather poor solvation of the bulky olefin in the liquid crystalline phases.
