One hydrogen bond doesn?t make a separation or does it? Resolution of amines by diacetoneketogulonic acid

12 Nov 2020

Preparation of diastereomeric salts. 100 mg of (?)-2,3:4,6-Di-O-isopropylidene-2-keto-L-gulonic acid, (diacetoneketogulonic acid, DAG) was dissolved in excess amount of the related amines and the crystals were harvested immediately after appearance. Many attempts were made to crystallize DAG with SMeBUAM (rate of evaporation was varied, as well as the crystallisation temperature) but all experiments yielded gels. Single Crystal X-Ray Diffraction. Diffraction data for all compounds were collected on a Bruker DUO APEX II diffractometer1 with graphite monochromated Mo K???radiation (? = 0.71073 ?) at 173 K using an Oxford Cryostream 700. Data reduction and cell refinement were performed using SAINT-Plus2 and the space groups were determined from systematic absences by XPREP3 and further justified by the refinement results. In all cases, the structures were solved in the aid of X-Seed4 by direct methods using SHELXS-975 and refined using full-matrix least-squares/difference Fourier techniques using SHELXL-97.5 The hydrogen atoms bound to carbon atoms were placed at idealized positions and refined as riding atoms with Uiso (H) = 1.2 Ueq (Ar-H, CH2) or 1.5 Ueq (CH3). Diagrams and publication material were generated using PLATON6 and X-Seed. Experimental details of the X-ray analyses are provided in Table S1. CIFs for each structure have been deposited with the Cambridge Structural Database (CCDC 950602-950607)