- Preparation of 2-Cyanobenzoic Acids from the Reaction of Bromobenzoic Acids with Arylacetonitriles and LDA
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The reaction of various bromobenzoic acids 1 with arylacetonitriles 3 in the presence of LDA at -70°C gave predominantly 2-cyanobenzoic acids 4 plus minor amounts of 3-(arylcyanomethyl)-benzoic acids 5 and debrominated benzoic acids 6. The reaction is thought to proceed through a benzyne-3-carboxylate intermediate 2, which is formed at -70°C upon the addition of the arylacetonitrile 3 to a solution of the appropriate lithium halobenzoate and excess LDA. The base-initiated generation of an aryne intermediate from a haloarene at such low temperatures is unprecedented. To confirm the orientation of the cyano and carboxylic acid groups, 4-methoxy-2-cyanobenzoic acid (4f) was converted to the corresponding anhydride (8) via phthalic acid (7) and to 3,3-dimethyl- and 3,3-di-n-butyl-2,3-dihydro-5-methoxy-4-(4-methoxyphenyl)-methyl-1H-isoindol-1- ones (9).
- Wang, Anlai,Maguire, John A.,Biehl, Ed
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p. 2451 - 2455
(2007/10/03)
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