Cyclohexyl isomer enrichment

Isolation and full characterization of each component of EL-499 has been elusive. However, isomer pure (1) was prepared by several methods including fractional recrystallization. (8) Cyclohexyl isomer enrichment was also achieved with EL-499 by selective hydrolysis. When EL-499 was refluxed in aqueous methanol with triethylamine for 16 hours, the appearance of 2-bromo-4-nitroaniline was observed by thin layer chromatography. Isolation of the carboxanilide products as a single band from column chromatography gave >99% (1) as evidenced from its FI9 NMR spectrum (Figure 3), which exhibited no detectable trifluoromethyl absorption and indicated that under these conditions the carboxanilides (2) were more reactive than (1). ... 

Figure 4. Cyclohexyl isomer Enrichment by Electro-fluorofragmentation.

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