With the redesign of three chemical steps, the throughput of the valsartan manufacturing process could be significantly increased, and with the substitution of chlorobenzene with cyclohexane in the bromination of 4′-methyl-biphenyl-2-carbonitrile (6) to 4′bromomethyl-biphenyl-2-carbonitrile (5), halogenated solvents are no longer used in the whole valsartan production process. The alkylation of (S)-2-amino-3-methyl-butyric acid benzyl ester (8) with 4′-bromomethyl-biphenyl-2-carbonitrile (5), and the acylation of (S)-2-[(2′-cyano-biphenyl-4-ylmethyl)-amino]-3-methyl-butyric acid benzyl ester (4) to (S)-2-[(2′-cyano-biphenyl-4-ylmethyl)pentanoyl-amino]-3-methyl-butyric acid benzyl ester (3) were thoroughly modified. In the acylation of 4 to 3, N-ethyldiisopropylamine was replaced by aqueous sodium hydroxide by using the conditions of the Schotten-Baumann reaction, leading to a better quality of intermediate 3. In the alkylation of 8 with 5, N-ethyldiisopropylamine was indirectly replaced by aqueous sodium hydroxide. The reaction runs under homogenous conditions with (S)-2-amino-3-methyl-butyric acid benzyl ester (8) acting as acceptor for hydrobromic acid; recycling of 8 is performed by extraction with aqueous sodium hydroxide.

The manufacturing process for lumefantrine, 2, one of the two active principles in the fixed-dose combination of the antimalarial drug Coartem, was reworked. For the conversion of 2-chloro-1-(2,7-dichloro-9H-fluoren-4-yl)ethanone, 5, to 2-dibutylamino-1-(2,7-dichloro-9H-fluoren-4-yl)ethanol, 8, a onepot process was developed that eliminated isolation of the epoxide 2-(2,7-dichloro-9H-fluoren-4-yl)oxirane, 7. Significant increase in throughput was achieved by applying new reaction and crystallization conditions for the Knoevenagel condensation of 2-dibutylamino-1-(2,7-dichloro-9H-fluoren-4-yl)ethanol, 8, to 2-dibutylamino-1-{2,7-dichloro-9-[1-(4-chlorophenyl)meth-(Z)ylidene]-9H-fluoren-4-yl}ethanol, 2.

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A novel industrial process for the antiepileptic drug oxcarbazepine 1 has been developed. Unlike the old process, the new process is free from halogenated solvents and can be performed in standard production equipment. It starts from commercially available 1,3-dihydro-1-phenyl-2H-indol-2-one 10. In the key step, an electrophilic ring closure reaction of 2-[(methoxycarbonyl)phenylamino] benzeneacetic acid 5 to 10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxylic acid methyl ester 6 in poly phosphoric acid was applied. For the manufacture of 5, a highly efficient process using a dianion strategy was developed.