The first proton sponge-based amino acids: synthesis, acid-base properties and some reactivity

The first hybrid base constructed from 1,8-bis(dimethylamino)naphthalene (proton sponge or DMAN) and glycine, N-methyl-N-(8-dimethylamino-1-naphthyl)aminoacetic acid, was synthesised in high yield and its hydrobromide was structurally characterised and used to determine the acid-base properties via...

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Bibliographic Details
Published in:Organic & biomolecular chemistry 2015-08, Vol.13 (31), p.8524-8532
Main Authors: Ozeryanskii, Valery A, Gorbacheva, Anastasia Yu, Pozharskii, Alexander F, Vlasenko, Marina P, Tereznikov, Alexander Yu, Chernov'yants, Margarita S
Format: Article
Language:English
Subjects:
Amino Acids - chemical synthesis
Amino Acids - chemistry
Chemistry Techniques, Synthetic
Hydrolysis
Models, Molecular
Molecular Conformation
Oxidation-Reduction
Protons
Quantum Theory
Temperature
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Summary:The first hybrid base constructed from 1,8-bis(dimethylamino)naphthalene (proton sponge or DMAN) and glycine, N-methyl-N-(8-dimethylamino-1-naphthyl)aminoacetic acid, was synthesised in high yield and its hydrobromide was structurally characterised and used to determine the acid-base properties via potentiometric titration. It was found that the basic strength of the DMAN-glycine base (pKa = 11.57, H2O) is on the level of amidine amino acids like arginine and creatine and its structure, zwitterionic vs. neutral, based on the spectroscopic (IR, NMR, mass) and theoretical (DFT) approaches has a strong preference to the zwitterionic form. Unlike glycine, the DMAN-glycine zwitterion is N-chiral and is hydrolytically cleaved with the loss of glycolic acid on heating in DMSO. This reaction together with the mild decarboxylative conversion of proton sponge-based amino acids into 2,3-dihydroperimidinium salts under air-oxygen was monitored with the help of the DMAN-alanine amino acid. The newly devised amino acids are unique as they combine fluorescence, strongly basic and redox-active properties.
ISSN:1477-0520
1477-0539
DOI:10.1039/c5ob01065a