The effect of the electronic nature of the para substituent on the aromatic ring of 2‐aryloxypropionyl chlorides on the stereochemical outcome of the acylation of 3,4‐dihydro‐3‐methyl‐2H‐[1,4]benzoxazine and its 7,8‐difluoro‐containing analogue has been studied. The geometries of the diastereoisomeric transition states and the corresponding Gibbs free enthalpies of activation were determined through DFT calculations at the COSMO‐CH2Cl2‐B3LYP‐D3‐gCP/def2‐TZVP (or def2‐SVP)//B3LYP‐D3‐gCP/def2‐SVP level of theory. It has been found that a low‐cost quantum chemical calculation at a chosen level of theory describes well the quantitative dependence of the selectivity of acylation on the structures of the reagents. The obtained results indicate that aromatic interactions between the reagents play a significant role in the process of stereodifferentiation, ensuring high selectivity of the acylation of benzoxazines with 2‐aryloxyacyl chlorides.
Recent publications on the key preparation methods of the enantiomers of 2-aryloxy carboxylic acids are summarized and comparative analysis of the methods is given. The information is arranged according to the type of the starting compound, being classified into syntheses from enantiomerically pure chiral precursors and syntheses from prochiral precursors, which imply generation of an asymmetric centre in the substrate molecule. Data on the chemical resolution of racemic mixtures of the title compounds are addressed in a separate Section. Attention is focused on the preparation of practically valuable 2-aryloxy acids. Examples of biologically active derivatives of 2-aryloxy carboxylic acids are given.
The bibliography includes 121 references.
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