AUTHOR=Yang Shiwei , Bian Guangling , Sa Rongjian , Song Ling 

TITLE=Assigning the Absolute Configurations of Chiral Primary Amines Based on Experimental and DFT-Calculated 19F Nuclear Magnetic Resonance

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00318

DOI=10.3389/fchem.2019.00318

ISSN=2296-2646

ABSTRACT=<p>In this work, a novel method for assigning the absolute configuration of a chiral primary amine has been developed based on the experimental and DFT-calculated <sup>19</sup>F NMR chemical shift differences of its derived two fluorinated amides by reacting with two enantiomers of a chiral derivatizing agent FPP (α-fluorinated phenylacetic phenylselenoester) separately. Comparing the experimental chemical shift difference <inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>Δ</mml:mo><mml:msubsup><mml:mrow><mml:mo>δ</mml:mo></mml:mrow><mml:mrow><mml:mo>α</mml:mo><mml:mo>-</mml:mo><mml:mi>F</mml:mi></mml:mrow><mml:mrow><mml:mi>R</mml:mi><mml:mo>,</mml:mo><mml:mi>S</mml:mi></mml:mrow></mml:msubsup></mml:math></inline-formula> of (R)-FPA-amide/(S)-FPA-amide with the calculated Δδ<sub>α-F<sup><italic>R,S</italic></sup></sub> of (R)-FPA-(R)-amide/(S)-FPA-(R)-amide, if the experimental Δδ<sub>α-F<sup><italic>R,S</italic></sup></sub> has the same symbol (positive or negative) as one of the theoretical Δδ<sub>α-F<sup><italic>R,S</italic></sup></sub>, the assigned configuration of the amine is considered to be consistent with the theoretical one. Our method could be applied to a broad substrate scope avoiding wrong conclusion due to empirical judgment.</p>