title: Linear and branched phospha[n]triangulanes.
abstract: Novel, highly stable, linear and branched mono- and diphospha[n]triangulanes were synthesized in high yields by the CuCl-catalyzed phosphinidene addition to spirocyclopropanated methylenecyclopropanes and bicyclopropylidenes. The effect of spirofusion on the electronic properties of these esthetically attractive phosphacycles is apparent from X-ray single crystal structure analyses, which reveals a tightening of the phosphirane ring on additional spirocyclopropanation, and from the NMR features that show deshielded chemical shifts for the ring-phosphorus and -carbon atoms. Steric factors play a role in the addition reaction when the substrate alkene carries a second sphere of spirocyclopropane rings and causes the formation of 2-phosphabicyclo[3.2.0]heptenes in small amounts. These by-products most probably result from addition of the [PhP(Cl)W(CO)(5)]-Cu-L (L=alkene or solvent) reagent to the spirocyclopropanated bicyclopropylidene to give an intermediate sigma-complex, which subsequently, facilitated by steric factors, undergoes a cyclopropylcarbinyl to cyclobutyl ring expansion followed by a [1,3]-sigmatropic shift.
authors.affiliation: Department of Organic and Inorganic Chemistry, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
authors.forename: J Chris
authors.initials: JC
authors.lastname: Slootweg
authors.forename: Frans J J
authors.initials: FJ
authors.lastname: de Kanter
authors.forename: Marius
authors.initials: M
authors.lastname: Schakel
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Sergei I
authors.initials: SI
authors.lastname: Kozhushkov
authors.forename: Armin
authors.initials: A
authors.lastname: de Meijere
authors.forename: Koop
authors.initials: K
authors.lastname: Lammertsma
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared
chemical_list: D009943:Organophosphorus Compounds