Reaction of indole-2,3-dicarboxylic anhydride with methylmagnesium bromide and phenylmagnesium bromide gave 2-acetyl-and 2-benzoyl-indole-3carboxylic acids, but with tert-butylmagnesium chloride, 3-pivaloylindnle-2carboxylic acids were obtained as the main products. Treatment of 2-acylindole-3-carboxylic acids with copper chrornite in quinoline or potassium hydroxide gave the corresponding 2-acylindoles.We have reported that the reduction of I-benzylindole-2,3-dicarboxylic anhydride (3b) with sodium borohydride gave a 2-hydroxymethylindole-3-carboxylic acid, which was converted to murrayaquinone-A via a Diels-Alder reaction of 4H-furo[3,4-blindole with methyl aclylate.'Reduction of the 2-carbonyl group of 3b is much easier than that of the 3-carbonyl group, because a nitrogen in the indole is more enolizable with the 3-carbonyl group than the 2-carbonyl group.2 Reaction of substituted phthalic anhydrides with Grignard reagents was controlled by electronic and steric factors.3 However, in reaction of pyridinedicarboxylic anhydride with Grignard reagents4 and l-benzenesulfonyl-2-lithioindole,5 a nitrogen in the pyridine decides the reactivity of the anhydride toward nucleophiles. In this paper we report the reactivity of 1-henzyl-(3b) and I-benzenesulfonylindole-2,3-dicarboxylic anhydrides (3c) with Grignard reagents and the synthesis of 2-acylindoles.The anhydrides (3b,c) were prepared from dimethyl indole-2,3-dicarboxylate (116 as follows. Hydrolysis Scheme 1 -
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