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3036052 
Journal Article 
The first proton sponge-based amino acids: synthesis, acid-base properties and some reactivity 
Ozeryanskii, VA; Gorbacheva, AY; Pozharskii, AF; Vlasenko, MP; Tereznikov, AY; Chernov'yants, MS 
2015 
1 
Organic and Biomolecular Chemistry
ISSN: 1477-0520
EISSN: 1477-0539 
13 
31 
8524-8532 
English 
26159785 
WOS:000358733100020 
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.