89361-81-9Relevant articles and documents
A new synthesis of 2-azabicyclo[2.1.1]hexanes
Lescop,Mevellec,Huet
, p. 4187 - 4193 (2001)
An efficient synthesis of the 2-azabicyclo[2.1.1]hexane ring system has been accomplished starting from cis-cyclobut-3-ene-1,2-dicarboxylic anhydride 7, which was prepared using a photochemical method. The key step of this new strategy involved a stereoselective electrophilic addition of phenylselenyl bromide to the double bond of cyclobutene dicarbamate 16 derived from 7. The subsequent ring closure of 17a in the presence of sodium hydride afforded the 2-azabicyclohexane compound 18 with a satisfying overall yield. Reductive removal of the phenylselenyl group and subsequent deprotection led rapidly to the amino derivative 4a functionalized on the carbon ring. Syntheses of the hydroxy and carboxylic derivatives 4b,c were then achieved from the intermediary disulfonamide 23. Displacement of the activated amino group by potassium acetate yielded hydroxy derivative 4b after three additional steps. Finally, oxidation of the alcohol function of 4b under Jones conditions followed by hydrogenolysis afforded the carboxylic derivative 4c, which is the first reported β-isomer of 2,4-methanoproline 1.
Folding and self-assembling with β-oligomers based on (1R,2S)-2-aminocyclobutane-1-carboxylic acid
Torres, Elisabeth,Gorrea, Esther,Burusco, Kepa K.,Da Silva, Eric,Nolis, Pau,Rua, Federico,Boussert, Stephanie,Diez-Perez, Ismael,Dannenberg, Samantha,Izquierdo, Sandra,Giralt, Ernest,Jaime, Carlos,Branchadell, Vicen,Ortuno, Rosa M.
experimental part, p. 564 - 575 (2010/05/12)
Improved methodologies are provided to synthesize (1R,2S)-2- aminocyclobutane-1-carboxylic acid derivatives and their incorporation into β-peptides of 2-8 residues bearing different N-protecting groups. The conformational analysis of these oligomers has been carried out by using experimental techniques along with theoretical calculations. This study shows that these oligomers adopt preferentially a strand-type conformation in solution induced by the formation of intra-residue six-membered hydrogen-bonded rings, affording cis-fused [4.2.0]octane structural units that confer high rigidity on these β-peptides. Moreover, all of them are prone to self-assemble producing nano-sized fibres, as evidenced by TEM, AFM and SPFM, and, in some instances, they also form gels. These techniques and molecular modelling allowed us to suggest an aggregation model for the assembly structures in which a parallel molecular-arrangement is preferred and the conformation is similar to that observed in solution. According to this model, both hydrogen-bonding and hydrophobic interactions would account for formation of the assemblies.
