Benzocaine → 4-[(2,3-dihydro-1H-indole-6-carbonyl)-amino]-benzoic acid ethyl ester

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Reaction Steps

4-{[1-(3,5-Dichloro-benzenesulfonyl)-2,3-dihydro-1H-indole-6-carbonyl]-amino}-benzoic acid, MS (ISP): m/e=488.9 (M−H), was prepared in analogy to example 14, steps 1 to 6. Step 1 was performed starting from 1H-indole-6-carboxylic acid methyl ester, which was reduced to 2,3-dihydro-1H-indole-6-carboxylic acid methyl ester (see also example 34). This was protected in step 2 to 2,3-dihydro-indole-1,6-dicarboxylic acid 1-tert-butyl ester 6-methyl ester, which was then hydrolyzed to 2,3-dihydro-indole-1,6-dicarboxylic acid 1-tert-butyl ester in step 3. Step 4 was performed using 4-amino-benzoic acid ethyl ester, yielding 4-[(2,3-dihydro-1H-indole-6-carbonyl)-amino]-benzoic acid ethyl ester. This was reacted with 3,5-dichloro-benzenesulfonyl chloride in step 5, yielding 4-{[1-(3,5-dichloro-benzenesulfonyl)-2,3-dihydro-1H-indole-6-carbonyl]-amino}-benzoic acid, which was hydrolyzed in step 6.

Provenance & Evidence