title: Efficient synthesis of 3-aminocyclobut-2-en-1-ones: squaramide surrogates as potent VLA-4 antagonists.
abstract: A novel series of uniquely functionalized 3-aminocyclobut-2-en-1-ones has been prepared by facile condensation of a variety of cyclobuta-1,3-diones with a phenylalanine-derived primary amine. These systems subsequently lend themselves to substitution at C-2 by reaction with a variety of electrophilic reagents including N-halosuccinimides, sulfenyl chlorides, and Eschenmoser's salt. Compounds from this novel series are potent antagonists of VLA-4. [reaction: see text]
authors.affiliation: Medicinal Chemistry, Celltech Group plc, 216 Bath Road, Slough SL1 4EN, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Brand
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: de Candole
authors.forename: Julien A
authors.initials: JA
authors.lastname: Brown
mesh_terms: D003503:Cyclobutanes / Q000737:chemistry* / Q000494:pharmacology*; D007202:Indicators and Reagents; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors*; D007659:Ketones / Q000138:chemical synthesis* / Q000494:pharmacology*; D010649:Phenylalanine / Q000031:analogs & derivatives
chemical_list: D003503:Cyclobutanes; D007202:Indicators and Reagents; D039041:Integrin alpha4beta1; D007659:Ketones; D010649:Phenylalanine