The first proton sponge-based amino acids: synthesis, acid-base properties and some reactivityElectronic supplementary information (ESI) available: Details of potentiometric titration; main fragmentation pathways of 2a+ under electron impact; DFT quantum-chemical calculations of amino acid 2a; data for thermolysis of 2a,b; copies of 1H and 13C NMR spectra; crystal data and structure refinement for compounds 6a and 12a. CCDC 1400689 and 1400690. For ESI and crystallographic data in CIF or other e

• 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
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c5ob01065a

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 (p K a = 11.57, H 2 O) 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. The first hybrid bases constructed from 1,8-bis(dimethylamino)naphthalene and glycine or alanine residues were synthesised and structurally characterised and unusual channels of their reactivity revealed.