Structural, surface, and computational analysis of two vitamin-B1 crystals with sulfonimide-based anions

Two crystals incorporating the thiamine·HCl cation and the fluorinated anion 1,3-disulfonylhexafluoropropyleneimide have been characterized via single-crystal X-ray diffraction. The host-guest interactions of thiamine with the anions are analyzed and characterized using Hirshfeld surface analysis. The cations in both structures form a dimer in the solid-state via reciprocal hydrogen bonding through the amine and hydroxyl moieties. Additional investigation into the interactions responsible for dimer formation found that the sulfur atom in the thiazolium ring interacting with several hydrogen atoms to form stabilizing interactions. These interactions in the dimer are further analyzed using reduced density gradient analysis and the results are correlated to the fingerprint plots derived from the Hirshfeld surfaces. Moreover, specific interactions are observed from the cyclical anions, with both the fluorine and sulfonyl oxygen atoms participating in bridging interactions, displaying the diverse host-guest properties of thiamine.

Synthetic Approaches to Chiral Non-C 2-symmetric N-Heterocyclic Carbene Precursors

N-Heterocyclic carbenes and their metal complexes have found applications in many organic transformations. Apart from the privileged C 2-symmetry present in modern enantioselective catalysis, ligands bearing C 1-symmetry have witnessed growing attention due to the better control of process stereoselectivity in many cases. The present review summarizes, for the first time, the seminal synthetic efforts for the preparation of N-heterocyclic carbene precursors exhibiting C 1-symmetry. The well-established methods will be discussed in the light of recent achievements, giving a direct opportunity for comparison of the existing methods, and simultaneously a chance to find the best synthetic pathway for the ideal chiral ligand.1 Introduction2 Five-Membered Rings2.1 Five-Membered Saturated (Imidazolinium) Ring2.1.1 Amino Alcohol Derivatives2.1.2 Amino Acid Derivatives2.1.3 Amine and Diamine Derivatives2.2 Five-Membered Unsaturated Ring2.2.1 Cyclization Strategy2.2.2 Functionalization of the Existing N-Imidazole Ring3 Triazolium Salts3.1 Substitution in Oxadiazolium Salts3.2 Lactam-Derived Triazolium NHC (The Leeper and Knight Methodology)3.3 Monoterpenoid-Derived NHC Triazolium Salts3.4 Modifications of the Existing Triazole Ring4 Thiazole-Derived Salts4.1 Cyclization of a Thiazolium Ring4.2 Modifications of the Existing Thiazole Ring5 Summary and Outlook

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

An analogue of thiamine having a furan ring in place of the thiazolium ring has been synthesised by a short and efficient route, involving gold(I)-catalysed cyclisation of an alkynyl alcohol to form the furan ring. The furan analogue of thiamine diphosphate (ThDP) was also made and tested for binding to and inhibition of pyruvate decarboxylase (PDC) from Zymomonas mobilis (overexpressed in E. coli with a N-terminal His-tag). It is a very strong inhibitor, with a K i value of 32.5 pM. It was also shown that the furan analogue of thiamine can be functionalised at the C-2 position, which will allow access to mimics of reaction intermediates of various ThDP-dependent enzymes.

2-Anilino-3-(2-hydroxypropyl)-4-methyl-1,3-thiazol-3-ium chloride

In the title compound, C13H17N2OS+·Cl−, the thiazolium ring mean plane makes a dihedral angle of 55.46 (9)° with the benzene ring. In the propanol group, the N—C—C—C and N—C—C—O torsion angles are 172.58 (15) and 52.9 (2)°, respectively, and the S—C—C—C torsion angle is 178.99 (18)°. In the crystal, molecules are linked by O—H...Cl and N—H...Cl hydrogen bonds, forming zigzag chains along [001]. There is also a C—H...Cl interaction present.