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[201551-23-7] C18H20N4O2 (MW 324.38) InChI = 1S/C18H20N4O2/c23-17(15-9-3-5-11-19-15)21-13-7-1-2-8-14(13)22-18(24)16-10-4-6-12-20-16/h3-6,9-14H,1-2,7-8H2,(H,21,23)(H,22,24)/t13-,14-/m1/s1 InChIKey = BVYFDUZVVBXFBQ-ZIAGYGMSSA-N (chiral bis-picolinic amide ligand for metal complexes used in a variety of asymmetric processes, particularly in regio- and enantioselective allylic alkylations) Alternate Name: bpchH2. Physical Data: mp 172–173 °C (recrystallized from EtOH); (R,R)-bpchH2: , (c 1.3, CHCl3). Solubility: soluble in chloroform, EtOAc, pyridine; sparingly soluble in ethanol; insoluble in hexanes. Form Supplied in: White solid. Analysis of Reagent Purity: 1IR: 3345, 2151, 1650, 1513, 1154, 750, 689 cm−1. 1H NMR (CDCl3): 8.50–8.48 (m, 2H), 8.21 (br s, 2H), 8.05–8.03 (m, 2H), 7.73–7.69 (m, 2H), 7.33–7.30 (m, 2H), 4.04 (br s, 2H), 2.20–2.15 (m, 2H), 1.82 (m, 2H), 1.46–1.41 (m, 4H). 13C NMR (CDCl3): 164.6, 149.8, 148.2, 137.1, 126.0, 122.1, 53.3, 32.7, 24.9. Preparative Methods: the ligand can be obtained through reaction of 2 equiv of 2-pyridinecarboxylic acid with (1R,2R)-1,2-diaminocyclohexane using Mukaiyama's reagent3 or via the acid chloride.1, 2 N,N′-(1R,2R)- and N,N′-(1S,2S′-1,2-cyclohexanediylbis-2-pyridinecarboxamide are synthesized in 84–92% yield by the activation of 2-picolinic acid with CDI in THF followed by the addition of the appropriate chiral 1,2-diaminocyclohexane.2 This procedure allows the synthesis of N,N′-(1S,2S)-1,2-cyclohexanediylbis-2-pyridinecarboxamide on a 2.5 kg scale in 86% yield. N,N′-(1R,2R)-1,2-cyclohexanediylbis-2-pyridinecarboxamide can also be obtained in 85% yield by the condensation of (1R,2R)-1,2-diaminocyclohexane with 2 equiv of picolinic acid activated by EDC/HOBT in chloroform.5 Purification: recrystallization from chloroform. Column chromatography on silica gel and/or recrystallization from ethanol. Handling, Storage, and Precautions: relatively safe reagent; no special instructions for its storage and handling are mentioned in the literature. Proper caution should be used as with all picoline amide reagents. Stable at room temperature. The compounds are registered to be harmful if swallowed as well as to cause skin and serious eye irritation and also respiratory irritation. Should be stored between 2 and 8 °C. |
