4- HALOBENZOYL CHLORIDES

PREPARATION OF 4-ALKYL- AND 4-HALOBENZOYL CHLORIDES 4-PENTYLBENZOYL CHLORIDE... 

This method is based on that of Fahim,4 who isolated 4-alkylbenzoic acids in 40-60% yields by hydrolysis of the corresponding acid chlorides. The present improved procedure includes those conditions believed to be optimum for a one-step synthesis of 4-substituted benzoyl chlorides in good yields and apparently free of positional isomers, as indicated by gas chromatography/mass spectroscopy as well as H and 13C NMR analyses. The procedure has been used successfully for the synthesis of 4-halobenzoyl chlorides and several other aryl acid chlorides,5 6 as well as for 4-alkylbenzoyl chlorides up through the decyl derivative. Some of these results are summarized in Table 1. The reaction has been run on a 1-mol scale by the submitters with no difficulty. 

An example of this displacement between a pyridine nitrogen atom and an aryl halide is shown in Scheme 21. When 2-pyridyl acetates 138 were C-acylated with 2-halobenzoyl chlorides, the enolized products 139 resulting from the reaction suffered an intramolecular nucleophilic attack of the pyridine nitrogen atom onto the ipso-position to give benzo[c]quinolizinium salts 140 as intermediates. Loss of HC1 gas from 140 afforded benzo[c]quinolizine derivatives 141 <2002JOC2082>. 

Cyclization of 2-halobenzoyl chlorides with binucleophiles as a convenient method for the construction of bi- and polycyclic A-, 0-, and S heterocycles 04IZV1091. 

Aroyl chlorides. The reaction of oxalyl chloride with aluminum chloride in CH2CI2 generates carbon monoxide and phosgene Caution /) On addition of an alkyl- or a halobenzene at 0°, p-alkyl- or p-halobenzoyl chlorides are obtained in high yield and in excellent purity. ... 

A general indole synthesis involves reaction of an o-nitrotoluene derivative with DMF dimethyl acetal in refluxing DMF (eq 12). - The initially formed o-nitroaryl-substituted ( )-MiV-dimethylenamine is submitted to catalytic hydrogenation to give the indole by spontaneous cyclization. According to a variation of this methodology, 2-arylindoles are readily available by reaction of o-nitrotoluene with DMF diethyl acetal and o-halobenzoyl chloride. This reaction proceeds via benzoylation of the respective enamine. 

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