Synthesis, structures, and strain energies of dispirophosphiranes. Comparisons with dispirocyclopropanes

Mark J.M. Vlaar, Maarten H. Lor, Andreas W. Ehlers, Marius Schakel, Martin Lutz, Anthony L. Spek, Koop Lammertsma

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17 Citations (Scopus)


Six novel dispirophosphirane complexes have been synthesized from the reaction of bicycloalkylidenes with the electrophilic phosphinidene complex PhPW(CO)5. They contain a central phosphirane ring, which is spirofused on one side to a cyclopropane or cyclobutane ring and on the other side with a three-, four-, five-, or six-membered ring. Their crystal structures and MP2/631G*-computed geometries for simplified parent systems suggest that spirofusion with small rings results in a tightening of the central three-membered phosphaheterocycle, while spirofusion with larger rings results in a relaxation of the phosphirane geometry. Similar theoretical predictions are made for the corresponding annulated hydrocarbons. Strain energies for both the hydrocarbon and phosphorus series of structures have been calculated at G3(MP2). Whereas the [3]triangulane hydrocarbon and phospha[3]triangulane have a significant excess strain of 8.1 and 5.2 kcal/mol per spiroatom, respectively, the excess strain for systems spirofused with larger rings are negligible for the hydrocarbons and even negative for the phosphorus-containing species because of hyperconjugative stabilization.

Original languageEnglish
Pages (from-to)2485-2493
Number of pages9
JournalJournal of Organic Chemistry
Issue number8
Publication statusPublished - 19 Apr 2002
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry


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