Regioselective formation of a 2,3-oxaphosphabicyclo[2.2.2]octene 3-oxide in Baeyer–Villiger type oxidation; a dual pathway for its fragmentation

Abstract

The O-insertion reaction of a 7-phos- phanorbornene (3) unsubstituted on the double- bond gave the corresponding 2,3-oxaphosphabicyclo- [2.2.2]octene oxide (4a) in a regioselective manner that was useful in the fragmentation-related phosphonylation of alcohols. Both the UV-light mediated and the thermoinduced phosponylation accomplished on the bridged P-heterocycle (4a) were found to be sensitive toward steric factors, suggesting that beside the well-known elimination–addition reaction path taking place via metaphosphonate (11), a competitive novel addition--elimination route involving an intermediate with a pentacoordinated P-atom (12) is also present. This was confirmed by the kinetic consideration of our experimental data. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:369–375, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20213