O Bromobenzoyl chloride

The carboxylic acid in this reaction is 2-bromobenzoic acid. By dropping the -oic acid ending of the I.U.P.A.C. name and replacing it with -oyl chloride, we can name the product of this reaction 2-bromobenzoyI chloride. It is equally correct to name this compound o-bromobenzoyl chloride. 

Preparation by acylation of 2,6-di-tert-butylphenol with o-bromobenzoyl chloride in the presence of aluminium chloride (31%) [860], according to [857]. 

Also obtained by reaction of o-bromobenzoyl chloride with anisole in the presence of aluminium chloride in chloroform at 20° for 12 h (89%) [1614]. 

SYNTHESIS The starting material 3,5-dimethoxy-4-bromobenzoic acid (made from the commercially available resorcinol by the action of methyl sulfate) was a white crystalline solid from aqueous EtOH with a mp of248-250 °C. Reaction with thionyl chloride produced 3,5-dimethoxy-4-bromobenzoyl chloride which was used as the crude solid product, mp 124-128 °C. This was reduced with tri-O-(t)-butoxy lithium aluminumhydride to produce 3,5-dimethoxy-4-bromobenzaldehyde which was recrystallized from aqueous MeOH and had a mp of 112-114 °C. Anal. (C9H9BrO,) C,H. This aldehyde, with nitroethane and anhydrous ammonium acetate in acetic acid, was converted to the nitrostyrene l-(3,5-dimethoxy-4-bromophenyl)-2-nitropropene, with a mp of 121-121.5 °C. Anal. (CnHl2BrN04) C,H,N. This was reducedat low temperature withjustone equivalent of LAH, to minimize reductive removal of the bromine atom. The product 3,5-dimethoxy-4-bromoamphetamine hydrochloride (4-BR-3,5-DMA) was isolated in a 37% yield and had a mp of 221-222 °C. Anal. (C,, H17BrClN02) C,H,N. 

Pyridones may be selectively acylated at oxygen by treatment with acetyl chloride in acetone in the presence of potassium carbonate <2001JOC3646>. 2-Pyridones are also selectively O-acylated with 2-bromobenzoyl chlorides in high yield using potassium carbonate and tetrabutylammonium bromide (TBAB) in acetone <2003T3009>. For example 3-methoxy-2(17/)-pyridone is acylated in 88% yield by 2-bromobenzoyl chloride under these conditions (Equation 73). 

The absolute configuration of caryose was determined applying the Exciton Chiral Coupling to 36 [Fig. (8)], which is the di-O-p-bromobenzoyl derivative, obtained as the main product of the isopropylidenation of the monosaccharide equilibrium mixture (34a, 34b and 35) followed by esterification with p-bromobenzoyl chloride. The results obtained have suggested for caryose the absolute configuration... 

Unlike aryl chlorides, acyl chlorides are quite reactive, although not often used. Oxidative addition of palladium(O) to the acid chloride 5.44 generates an acyl palladium(II) complex 5.46 (Scheme 5.12). This may undergo decarbonylation or not prior to alkene insertion depending on the reaction conditions, and the substrate structure (Schemes 5.13 and 5.14). Acid chlorides are more reactive than aryl bromides and selective coupling at the two positions of p-bromobenzoyl chloride 5.53 with different alkenes is possible (Scheme 5.15). ... 

Preparation by demethylation of 4 -bromo-3-fluoro-4-methoxybenzophenone (SM) with 62% aqueous hydrobromic acid in acetic acid at 125°. SM was obtained by Friedel-Crafts acylation of o-fluoroani-sole with p-bromobenzoyl chloride in nitrobenzene in the presence of aluminium chloride [512],... 

By the use of substituted benzoyl chlorides, derivatives such as the penta-O-(p-bromobenzoyl)- and penta-0-(p-nitrobenzoyl)-D-glucoses have been prepared. 

---