Crystal and molecular structure of 2-aminoadamantane-2-carboxylic acid hydrobromide

Abstract

2-Aminoadamantane-2-carboxylic acid hydrobromide crystallizes in space group P21/c with a= 6.40, b= 11"62 and c= 15.38 ,~, fl= 95.2 °, Z=4. The structure was solved by the heavy-atom method with 1484 visual reflexions and refined to an R of 0.097. The substitution of the amino and the carboxyl group at C(2) of the adamantane does not significantly affect its highly symmetric cage-hke structure.In relation to amino acid structures, a rare occurrence of the C(11)-O(2) double bond trans to the nitrogen N about the C(2)-C(11) bond is observed in this structure. The nitrogen atom lies 1.07 A oat of the plane containing the carboxyl group and C(2).

Crystal structure of memantine–carboxyborane

“…The bond lengths [C1-O1 = 1.340 (4), C1-O2 = 1.227 (4) Å ] of the carboxylic acid group are in agreement with the data for related carboxylic acids and known amine-carboxyboranes (Gavezzotti, 2008;Spielvogel et al, 1980;Vyakaranam et al, 2002;Ayudhya et al, 2017). The C-C-C bond angles of the adamantine cage fall within the expected ranges and the N1-C2 bond length at 1.504 (4) Å is comparable with previously reported values in aminoadamantane structures (Donohue & Goodman, 1967;Chacko & Zand, 1973).…”

“…However, numerous crystal structures of the adamantane cage and its derivatives in various forms have been reported over many years (Nordman & Schmitkons, 1965;Chacko & Zand, 1973;SiMa, 2009;Glaser et al, 2011).…”

En route towards the peptide γ‐helix: X‐ray diffraction analyses and conformational energy calculations of Adm‐rich short peptides

“…We were also intrigued by the opportunity to expand the large conformational versatility of the class of C α -tetrasubstituted residues, already clearly demonstrated in our long-standing 3D-structural investigations, which goes from 3 10 and α-helices [9,10] to the fully-extended conformation [41]. In the crystal state, only the 3D-structures of the free Adm amino acid itself [39,42] and a few derivatives [36,39,[43][44][45][46][47] were reported. An NMR analysis of a terminally free tetrapeptide containing an Adm residue at position 3 was published [48] but without any discussion on its preferred conformation.…”

Computational study of the conformational preferences of the (R)‐8‐amino‐pentacyclo[5.4.0.02,6.03,10.05,9] undecane‐8‐carboxylic acid monopeptide

“…The incorporation of cage frameworks such as the 1-aminoadamantane into drugs should also have the added advantage that metabolic degradation is retarded by the inherent steric bulk of the cage skeleton, thus prolonging the activity and reducing the frequency of drug administration to the patient. On the other hand, incorporation of C α -tetrasubstituted α-amino acids with cage moieties, such as 2aminoadamantane-2-carboxylic acid (compound 2 Figure 1), into peptides produces receptor site specificity through the induction of a specific conformation to the ligand [17][18][19]. This has been particularly useful in areas such as antibacterial activity, anabolic action and analgesic activity [16].…”