Reaction of unsaturated phosphonate monoesters with bromo- and iodo(bis-collidine) hexafluorophosphates

Reaction of unsaturated phosphonate monoesters with bromo- and iodo(bis-collidine) hexafluorophosphates are reported to lead to the formation of five-to seven-membered phostones by exo mode cyclizations. When the chains of the unsaturated phosphonate monoesters are substituted in a of the double bond by a dioxolane group endo mode cyclizations are observed. These cyclizations give rise to the formation of 1,2-oxaphosphepane-2-oxide and 1,2-oxaphosphocane-2-oxide. (c) 2007 Elsevier Ltd. All rights reserved.