Cyclobutane-Containing Scaffolds as Useful Intermediates in the Stereoselective Synthesis of Suitable Candidates for Biomedical Purposes: Surfactants, Gelators and Metal Cation Ligands

Abstract

Efficient and versatile synthetic methodologies are reported for the preparation of products that are suitable candidates to be used as surfactants, gelators for hydroxylic solvents or metal cation ligands, with potential use in several fields including biomedical applications. The common structural feature of all the synthesized products is the presence of a cis or trans-1,2- or cis-1,3-difunctionalized cyclobutane ring. In the two first cases, the key intermediates including enantiomerically pure 1,3-diamines and 1,3-amino alcohols have been prepared from β-amino acid derivatives obtained, in turn, from a chiral half-ester. This compound is also precursor of γ-amino esters. Furthermore, two kind of polydentate ligands have also been synthesized from a symmetric 1,5-diamine obtained from norpinic acid, which was easily prepared from commercial verbenone.

Keywords: amphiphiles; cation ligands; cyclobutane; gelators; surfactants.

Scheme 1

Retrosynthetic strategies to prepare the target products from suitable precursors.

Scheme 2

Synthetic route towards non-ionic or anionic amphiphiles.

Scheme 3

Synthesis of cationic amphiphiles and organogelators from cis- or trans-β-CBAA.

Scheme 4

Synthesis of ligands from 1,3-disubstituted cyclobutane scaffolds.