The perfluoroalkyl-BINOL-based chiral diketones are found to show very different fluorescence responses toward the enantiomers of chiral amino alcohols in the fluorous phase. These molecular sensors are potentially useful for high-throughput screening of chiral catalysts. Conducting the enantioselective fluorescent recognition in the fluorous phase can potentially minimize the interference of various reaction components in the measurement since most compounds cannot be dissolved in the hydrophobic and lipophobic fluorous solvents. This study expands the excellent chiral recognition ability of the BINOL-based sensors (ef = (IS-I0)/(IR-I0) value up to 60) to a variety of chiral secondary β-amino alcohols in the fluorous phase. The asymmetric ring opening reaction of meso- or racemic epoxides with amines affords a simple route to optically enriched β-amino alcohols that are building blocks for biologically active compounds and chiral auxiliaries or ligands in asymmetric synthesis. The perfluoroalkyl-BINOL-based sensor was investigated and applied as a tool for high-throughput screening of enantioselective ring opening reaction of meso-epoxides with aliphatic primary amines. By using both (S)-Sensor and (R)-Sensor (7.5 μM), two small portions (0.2 %) of the reaction mixture (1 mmol), and 4 mL solvents (FC-72/DCM = 96:4), both fluorescent intensity ratio (IS/IR) and sum (IS+IR) gave ee value, yield, as well as absolute configuration of the product within 2 minutes. Conventional chiral HPLC validated the results by derivation of the secondary β-amino alcohol product in 24 hours. Minimizing analysis cost, time, and chemical waste gives rise to high-throughput chiral catalyst screening.

Enantioselective fluorescent recognition of chiral secondary amino alcohols in the fluorous phase: Leading to high-throughput chiral catalyst screening

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.