Tris methane, formylation

In contrast with the azoles, diazoles and their benzo derivatives tend to react with dichlorocarbene to yield the tris(diazolyl)methanes, presumably via the initial formation of the N-dichloromethyl derivative [6, 13]. Only in more activated polymethyl derivatives does reaction occur at a ring carbon atom. In a similar manner (7.7.1.B), 2-chloropyridine and 2-chloroquinoline react with dichlorocarbene at the ring nitrogen atom to yield, after nucleophilic displacement of the chloro group, the 1 -dichloromethyl-2-oxo derivatives (13-25%) [14] (Scheme 7.38). 2-Chlorobenzothiazole reacts in an analogous manner, but other pyridine and quinoline derivatives fail to react. It is also noteworthy that the dichloromethyl group is unusually stable and is not converted into the formyl group. 

Formylation of the less reactive phenol and anisole with CO in HF-BF3 was found to require at least stoichiometric amount of the acid for effective transformation (50 equiv. of HF, 2 equiv. of BF3, 50 bar CO, 45°C).445 Conversion increases with increasing reaction time but results in decreasing paralortho ratios suggesting a change from kinetic control to thermodynamic control and the reversibility of formylation. Furthermore, the amount of byproducts (mainly diphenylmethane derivatives) originating from reactions between substrates and products also increases. Additional studies in ionic liquids showed that imidazolium cations with increased chain lengths—for example, l-octyl-3-methylimidazolium salts—are effective in the formylation process. This was attributed to the enhanced solubility of CO in the ionic liquid medium. Tris(dichloromethyl)amine, triformamide, and tris (diformylamino)methane have recently been applied in the formylation of activated aromatic compounds in the presence of triflic acid at low temperature (— 10 to 20°C) albeit yields are moderate.446... 

Methan (2-Formyl-pyrrolo)-(2-tri-methylsilyl-ethoxy)- E14a/2, 162 (Cl - N)... 

Tiithioorthoester Activation. Electron-rich aromatic rings undergo electrophilic aromatic substitution with tris(phenylthio) methane in the presence of DMTSF. Subsequent hydrolysis results in an aldehyde and a net electrophilic formylation . Intramolecular reaction between a tris(phenylthio)methane unit and an alcohol represents an approach to lactone formation which utilizes the chemoselectivity of DMTSF ... 

GC-MS-fragmentation patterns indicated the following secondary products isomers resulting from the formylation of toluene dimethylbenzophenone (30). di(methylphenyl)-methane ( ), tri(methylphenyl)methane (29) and di(methylphenyl)-methanol (26). The formation of the various side-products is explicable in terms of a two-step mechanism. 

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