title: Squaramides: physical properties, synthesis and applications.
abstract: Squaramides are remarkable four-membered ring systems derived from squaric acid that are able to form up to four hydrogen bonds. A high affinity for hydrogen bonding is driven through a concomitant increase in aromaticity of the ring. This hydrogen bonding and aromatic switching, in combination with structural rigidity, have been exploited in many of the applications of squaramides. Substituted squaramides can be accessed via modular synthesis under relatively mild or aqueous conditions, making them ideal units for bioconjugation and supramolecular chemistry. In this tutorial review the fundamental electronic and structural properties of squaramides are explored to rationalise the geometry, conformation, reactivity and biological activity.
authors.affiliation: Worldwide Medicinal Chemistry, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent, CT13 9NJ, UK. ian.storer@pfizer.com
authors.forename: R Ian
authors.initials: RI
authors.lastname: Storer
authors.forename: Caroline
authors.initials: C
authors.lastname: Aciro
authors.forename: Lyn H
authors.initials: LH
authors.lastname: Jones
mesh_terms: D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology; D003503:Cyclobutanes / Q000737:chemistry; D006635:Histamine H2 Antagonists / Q000737:chemistry / Q000627:therapeutic use; D006801:Humans; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D014456:Ulcer / Q000188:drug therapy
chemical_list: D000577:Amides; D002614:Chelating Agents; D003503:Cyclobutanes; D006635:Histamine H2 Antagonists; C030042:squaric acid