Unexpected tetrahydrophosphepine oxides by the ring enlargement of tetrahydrophosphinine oxides
Abstract
Reaction of the regioisomers (A and B) of tetrahydrophosphinine oxide 1 with NaOH–H2O–CHCl3 under PTC conditions affords tetrahydrophosphepine oxides 2A and 2B through an unexpected path involving isomerisation of 1 and cyclopropanation via Michael addition of CCl3–.