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Linear and Branched Phospha[ n ]triangulanes
Author(s) -
Slootweg J. Chris,
de Kanter Frans J. J.,
Schakel Marius,
Lutz Martin,
Spek Anthony L.,
Kozhushkov Sergei I.,
de Meijere Armin,
Lammertsma Koop
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500538
Subject(s) - phosphinidene , steric effects , chemistry , alkene , ring (chemistry) , cyclopropane , solvent , chemical shift , stereochemistry , reagent , catalysis , organic chemistry
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 σ‐complex, which subsequently, facilitated by steric factors, undergoes a cyclopropylcarbinyl to cyclobutyl ring expansion followed by a [1,3]‐sigmatropic shift.