An analysis of crystal structures of a series of fluoro-substituted phenylboronic acids is presented. Interplay between the structure of a basic H-bonded dimeric R 2 2 (8) synthon and a higher-order supramolecular organization is highlighted. The elucidation of hydrogen bonds formed by the boronic B(OH) 2 moiety is supported by energy calculations based on a one-dimensional H-bond model as well as by Hirshfeld surface analysis. The results revealed that intramolecular O−H•••F hydrogen bonds are insignificant compared to O−H•••O ones in dimers in controlling the syn−anti conformation of the boronic group. Depending on the strength of H-bonds in the basic motif, forces constituting so-called large synthons change from O−H•••O hydrogen bonds to stacking interactions. This differentiation entails the twist of the boronic group with respect to the phenyl ring. The large synthons serve as main building blocks for three-dimensional structures either by their close packing or by the aid of weak secondary interaction such as C−H•••π, O−H•••F, or C−H•••F hydrogen bonds. The observed isomorphism and polymorphism are discussed in relation to the packing of one-dimensional large synthons.

Table S1. Experimental (X-ray) and Theoretical (DFT-RB3LYP/6-311G(2df,p) level) Bond Lengths (Å) for Fluoro-substitued Phenylboronic Catechol Esters. page 2 Table S1. Experimental (X-ray) and Theoretical (DFT-RB3LYP/6-311G(2df,p) level) Bond Lengths (Å) for Fluoro-substitued Phenylboronic Catechol Esters.* 4fphb 26fphb 246fphb 345fphb pfphb O1-C7

The systematic analysis of the geometry of three-coordinate boron in boronic acid derivatives with a common [CBO2] skeleton is presented. The study is based on the bond-valence vector (BVV) model [Zachara (2007). Inorg. Chem. 46, 9760-9767], a simple tool for the identification and quantitative estimation of both steric and electronic factors causing deformations of the coordination sphere. The empirical bond-valence (BV) parameters in the exponential equation [Brown & Altermatt (1985). Acta Cryst. B41, 244-247] rij and b, for B-O and B-C bonds were determined using data deposited in the Cambridge Structural Database. The values obtained amount to rBO = 1.364 Å, bBO = 0.37 Å, rBC = 1.569 Å, bBC = 0.28 Å, and they were further used in the calculation of BVV lengths. The values of the resultant BVV were less than 0.10 v.u. for 95% of the set comprising 897 [CBO2] fragments. Analysis of the distribution of BVV components allowed for the description of subtle in- and out-of plane deviations from the `ideal' (sp(2)) geometry of boron coordination sphere. The distortions specific for distinct groups of compounds such as boronic acids, cyclic and acyclic esters, benzoxaboroles and hemiesters were revealed. In cyclic esters the direction of strains was found to be controlled by the ring size effect. It was shown that the syn or anti location of substituents on O atoms is decisive for the deformations direction for both acids and acyclic esters. The greatest strains were observed in the case of benzoxaboroles which showed the highest deviation from the zero value of the resultant BVV. The out-of-plane distortions, described by the vz component of the resultant BVV, were ascertained to be useful in the identification of weak secondary interactions on the fourth coordination site of the boron centre.

A one‐pot, two‐step synthesis of chiral 7‐oxa‐1‐azabicyclo[2.2.1]heptane derivatives from unprotected D‐xylose was achieved by an intramolecular 1,3‐dipolar cycloaddition of the N‐(γ‐alkenyl)‐substituted nitrone intermediate. The stereochemical course of the cycloaddition was altered by the addition of an achiral Lewis acid. The bicyclic byproducts were employed in a concise synthesis of two new enantiomeric piperidine‐type iminosugars.

The combination of a piperazine and boronic groups within one molecule can result in a totally novel biological activity. A series of benzyl piperazine derivatives of boronic acids have been obtained by the facile and effective method based on the amination-reduction reaction of 2-formylphenylboronic acid with N-substituted piperazines. The molecular and crystal structures of six novel derivatives have been investigated, along with Hirshfeld surface analysis and hydrogen bond energy estimation. The studied compounds display several structural features that make them promising candidates as biologically active compounds.