title: Experimental and computational study of the ring opening of tricyclic oxanorbornenes to polyhydro isoindole phosphonates.
abstract: Phosphonylated azaheterocycles are an important class of compounds with high biological potential as conformationally restricted bioisosteres of amino acids. Therefore, it is of interest to synthesize conformationally constrained amino phosphonates. We wanted to investigate possible routes via ring opening of alpha-amino phosphonates with an oxanorbornene skeleton, as these can be synthesized with high stereoselectivity. This was achieved using different Lewis acids, leading to a range of products. The reaction with TiCl(4) and FeCl(3) was modelled at a DFT level of theory to get insight in the pathways towards the corresponding products. To ease the work up, the Fe(iii) catalyst was coated on montmorillonite clay, but this accelerated aromatization after ring opening. Quenching the FeCl(3) catalyzed reaction mixture on celite caused complete aromatization.
authors.affiliation: Research group SynBioC, Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium.
authors.forename: Diederica D
authors.initials: DD
authors.lastname: Claeys
authors.forename: Christian V
authors.initials: CV
authors.lastname: Stevens
authors.forename: Bart I
authors.initials: BI
authors.lastname: Roman
authors.forename: Pieter
authors.initials: P
authors.lastname: Van De Caveye
authors.forename: Michel
authors.initials: M
authors.lastname: Waroquier
authors.forename: Veronique
authors.initials: V
authors.lastname: Van Speybroeck
mesh_terms: D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D006865:Hydrogenation; D054833:Isoindoles / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009636:Norbornanes / Q000737:chemistry*; D063065:Organophosphonates / Q000138:chemical synthesis*; D010100:Oxygen / Q000737:chemistry*
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; D054833:Isoindoles; D009636:Norbornanes; D063065:Organophosphonates; D010100:Oxygen