Abstract The synthesis of α-chloro-tetrahydrophosphinines by inter- or intramolecular [4+2] cycloaddition reactions involving unstabilized phosphaalkenes is presented. Conditions for a selective base-induced isomerisation of substituted dihydrophosphinines are precised. A tautomeric phosphaalkene/vinylphosphine equilibrium was for the first time evidenced.
Three representative phosphabicyclo[4.3.0]non-4-ene derivatives are formed in high yields and various diastereomeric forms by [4 + 2] intramolecular cycloadditions involving transient phosphaalkenes as dienophiles; complete diastereoselectivity is observed with the P-substituted derivative.