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1. Chiroptical sensing of amino acids, amines, amino alcohols, alcohols and terpenes with π-extended acyclic cucurbiturils

   https://doi.org/10.1039/​D1OB00345C  

   Hassan, Diandra S.; De los Santos, Zeus A.; Brady, Kimberly G.; Murkli, Steven; Isaacs, Lyle; Wolf, Christian (May 2021, Organic & Biomolecular Chemistry)

   null (Ed.)

   The efficiency and scope of two acyclic π-wall extended cucurbiturils, M2 and M3 , exhibiting rapidly interconverting helical conformers for chiroptical sensing of amines, amino acids, alcohols, and terpenes at micromolar concentrations in water is evaluated. The formation of 1 : 1 host–guest complexes results in spontaneous induction of circular dichroism signals that can be used for accurate determination of the absolute configuration and enantiomeric composition of the analyte based on a simple mix-and-measure protocol. 

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2. Rapid organocatalytic chirality analysis of amines, amino acids, alcohols, amino alcohols and diols with achiral iso(thio)cyanate probes

   https://doi.org/10.1039/D1SC02061G  

   Nelson, Eryn; Formen, Jeffrey S.; Wolf, C. (June 2021, Chemical Science)

   The widespread occurrence and significance of chiral compounds does not only require new methods for their enantioselective synthesis but also efficient tools that allow rapid determination of the absolute configuration, enantiomeric composition and overall concentration of nonracemic mixtures. Although chiral analysis is a frequently encountered challenge in the chemical, environmental, materials and health sciences it is typically addressed with slow and laborious chromatographic or NMR spectroscopic techniques. We now show with almost 40 analytes representing 5 different compound classes, including mono-alcohols which are particularly challenging sensing targets, that this task can be solved very quickly by chiroptical sensing with a single, readily available arylisocyanate probe. The probe reacts smoothly and irreversibly with amino and alcohol groups when an organocatalyst is used at room temperature toward urea or carbamate products exhibiting characteristic UV and CD signals above 300 nm. The UV signal induction is not enantioselective and correlated to the total concentration of both enantiomers, the concomitant generation of a CD band allows determination of the enantiomeric composition from the same sample, and the sense of the induced Cotton effect reveals the absolute configuration by comparison with a reference. This approach eliminates complications that can arise when enantiomerically impure NMR derivatizing agents are used and it outperforms time-consuming HPLC protocols. The generation of distinct UV and CD signals at high wavelengths overcomes issues with insufficient resolution of overlapping signals often encountered with chiral NMR solvating agents that rely on weak binding forces. The broad solvent compatibility is another noteworthy and important characteristic of this assay. It addresses frequently encountered problems with insufficient solubility of polar analytes, for example pharmaceuticals, in standard mobile phase mixtures required for chiral HPLC analysis. We anticipate that the broad application spectrum, ruggedness and practicality of organocatalytic chiroptical sensing with aryliso(thio)cyanate probes together with the availability of automated CD multi-well plate readers carry exceptional promise to accelerate chiral compound development projects at reduced cost and with less waste production. 

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3. Enantioselective Fluorescent Recognition of β‐Amino Alcohols by Stereoselective Cyclization

   https://doi.org/10.1002/ejoc.202200283  

   Tian, Jun; Yu, Shanshan; Guo, Hongyu; Zhu, Maoshuai; Lu, Kai; Jiang, Yixuan; Yang, Jiaqiao; Yu, Xiaoqi; Pu, Lin (May 2022, European Journal of Organic Chemistry)

   Abstract 2,2’‐Diformyl‐1,1’‐binaphthyl is found to exhibit highly enantioselective fluorescence enhancement in the presence of various β‐amino alcohols and base. It provides a new method to determine the enantiomeric composition of those substrates and has potential for high throughput analysis. Based on detailed spectroscopic analyses, it is proposed that a stereoselective cyclization of a β‐amino alcohol with the probe should occur to form a rigid macrocyclic intermediate, contributing to the greatly enhanced fluorescence. 

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4. γ-Amino Alcohols via Organocascade Reactions Involving Dienamine Catalysis

   https://doi.org/10.1021/jo3017007  

   Appayee, Chandrakumar; Fraboni, Americo J.; Brenner-Moyer, Stacey E. (September 2012, The Journal of Organic Chemistry)
5. Chiroptical sensing of unprotected amino acids, hydroxy acids, amino alcohols, amines and carboxylic acids with metal salts

   https://doi.org/10.1039/C9CC02525A  

   Lynch, Ciarán C.; De los Santos, Zeus A.; Wolf, Christian (May 2019, Chemical Communications)

   Optical chirality sensing of unprotected amino acids, hydroxy acids, amino alcohols, amines and carboxylic acids based on a practical mix-and-measure protocol with readily available copper, iron, palladium, manganese, cerium or rhodium salts is demonstrated. The generation of strong cotton effects allows quantitative ee analysis of small sample amounts with high speed. In contrast to previously reported assays the use of chromophoric reporter ligands and the control of metal coordination kinetics and redox chemistry are not necessary which greatly simplifies the sensing procedure with the benefit of reduced waste production and cost. 

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