14252-21-2Relevant academic research and scientific papers
Iron-Catalyzed Ortho C-H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand
Shang, Rui,Ilies, Laurean,Nakamura, Eiichi
supporting information, p. 10132 - 10135 (2016/08/31)
Iron-catalyzed C-H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis(2-(diphenylphosphanyl)phenyl)phosphanyl)-N,N-dimethylaniline (Me2N-TP), that allows us to convert an ortho C-H bond to a C-CH3 bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four ortho C-H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones.
Spectroscopic and product studies of the effect of para substituents on the reactivity of triplet bis(2,6-dimethylphenyl)carbenes
Hu, Yingmo,Ishikawa, Yui,Hirai, Katsuyuki,Tomioka, Hideo
, p. 2207 - 2218 (2007/10/03)
A series of diazobis(2,6-dimethylphenyl)methanes (1) bearing eight symmetrical para di-substituents have been prepared and photolyzed to generate the corresponding carbenes (2). Product analysis studies showed that carbenes (2) decay mainly either by dimerization to form tetra(aryl)ethylene (3) or by attack at an o-methyl group to afford 1,2-dihydrobenzocyclobutenes (4) by way of o-quinodimethanes (6) in solution. The zero-field splitting parameters, D and E, were measured in matrices of different viscosities and are analyzed in terms of a sigma-dot (σ.) scale of spin-delocalization substituent constants. Fairly good correlation with σ. was found for the D values of 32 in its minimum energy geometry. Stabilities of 32 were estimated either by measuring the temperature at which the triplet carbene signals disappeared upon thawing the matrix or by analyzing the decay kinetics of 32 in a degassed solution at room temperature. They are examined in terms of the D values in matrix at low temperature and in terms of product distributions in solution at room temperature.
