C−H⋅⋅⋅O Hydrogen‐Bond‐Assisted Carboxylate⋅⋅⋅Carboxylate Interactions in a Prevented Decarboxylation of N‐Acetate Isonicotinamide Betaine. Issue 1 (4th December 2019)

• Record Type: Journal Article
• Authors: Huang, Jing‐Ting; Hsu, Ching‐I; Wen, Hsin‐Yi; Wang, Yu‐Chieh; Shu, Youn‐Yuen; Lee, Kwang‐Ming
• Is Part Of: Asian journal of organic chemistry. Volume 9:Issue 1(2020)
• Page Start: 77
• Page End: 81
• Publication Date: 2019-12-04
• Subjects: decarboxylation -- zwitterions -- crystal structures -- hydrogen bonds -- noncovalent interactions; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.201900594
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: Two acetic acid functionalized isonicotinamide (or 4‐carbamoyl‐1‐(carboxymethyl) pyridin‐1‐ium) salts with Br − and BPh4 − anions have been prepared. The hydrophilic Br − and hydrophobic BPh4 − anions result in two salts having different solubilities in water and acetone. Further recrystallizations of Br − and BPh4 − salts from protic H2 O/THF and aprotic acetone/ether solvents gave single crystals of a non‐decarboxylated zwitterion (a isonicotiamide betaine) and a decarboxylated isonicotiamides salt at room temperature respectively. A carboxylate−carboxylate dimer motif was observed in the zwitterion crystal structure. Theoretical calculations by using the PBE1PBE method at the cc‐pVDZ level indicate the carboxylate−carboxylate dimer motif was stabilized by the C−H⋅⋅⋅O hydrogen bonding assisted carbonyl⋅⋅⋅carbonyl interaction. Abstract : It only costs a dimer : The effects of hydrophilic Br − and hydrophobic BPh4 − anions on the decarboxylation of acetic‐acid‐functionalized nicotinamide salts are presented herein. The Br − and BPh4 − salts recrystallized in protic H2 O/isopropanol and aprotic acetone solvents gave single crystals of the non‐decarboxylated zwitterion 1 and decarboxylated salt 3, respectively. A carboxylate–carboxylate dimer motif is observed in the crystal structure of zwitterion 1 . Theoretical calculations highlight the carboxylate–carboxylate dimer motif is stabilized by the C − H⋅⋅⋅O hydrogen bonding assisted carbonyl⋅⋅⋅carbonyl interaction . These results could highlight the importance of C−H−O hydrogen bonding formed by the nicotinamide and isonicotinamide cations, especially by NAD +, and they also indicate that the decarboxylation reaction of betaines could be facilitated by the hydrophobic BPh4 − anion in an aprotic solvent.