Neel, Andrew J. published the artcileEnantiodivergent Fluorination of Allylic Alcohols: Data Set Design Reveals Structural Interplay between Achiral Directing Group and Chiral Anion, Name: (3-Methoxy-5-methylphenyl)boronic acid, the publication is Journal of the American Chemical Society (2016), 138(11), 3863-3875, database is CAplus and MEDLINE.
Enantioselectivity values represent relative rate measurements that are sensitive to the structural features of the substrates and catalysts interacting to produce them. Therefore, well-designed enantioselectivity data sets are information rich and can provide key insights regarding specific mol. interactions. However, if the mechanism for enantioselection varies throughout a data set, these values cannot be easily compared. This premise, which is the crux of free energy relationships, exposes a challenging issue of identifying mechanistic breaks within multivariate correlations. Herein, we describe an approach to addressing this problem in the context of a chiral phosphoric acid catalyzed fluorination of allylic alcs. using aryl boronic acids as transient directing groups. By designing a data set in which both the phosphoric and boronic acid structures were systematically varied, key enantioselectivity outliers were identified and analyzed. A mechanistic study was executed to reveal the structural origins of these outliers, which was consistent with the presence of several mechanistic regimes within the data set. While 2- and 4-substituted aryl boronic acids favored the (R)-enantiomer with most of the studied catalysts, meta-alkoxy substituted aryl boronic acids resulted in the (S)-enantiomer when used in combination with certain (R)-phosphoric acids. We propose that this selectivity reversal is the result of a lone pair-π interaction between the substrate ligated boronic acid and the phosphate. On the basis of this proposal, a catalyst system was identified, capable of producing either enantiomer in high enantioselectivity (77% (R)-2 to 92% (S)-2) using the same chiral catalyst by subtly changing the structure of the achiral boronic acid.
Journal of the American Chemical Society published new progress about 725251-81-0. 725251-81-0 belongs to ethers-buliding-blocks, auxiliary class Boronic acid and ester,Benzene,Ether,Boronic Acids,Boronic acid and ester, name is (3-Methoxy-5-methylphenyl)boronic acid, and the molecular formula is C8H11BO3, Name: (3-Methoxy-5-methylphenyl)boronic acid.
Referemce:
https://en.wikipedia.org/wiki/Ether,
Ether | (C2H5)2O – PubChem