Highly functionalised (γ-azido/γ-fluoro-β-iodo/)vinyl derivatives from phosphorus based allenes or allenoates: I⋯O halogen bonding interactions

Abstract

Multifunctional γ-azido/γ-fluoro-β-iodo-vinyl phosphine oxides/phosphonates/esters/sulfone were synthesised by iodination followed by azidation/fluorination of phosphorus-based allenes or allenoates (allenyl esters) or a sulphur based allene. Surprisingly, the reaction of (γ,β)-diiodo-vinyl-phosphonate with TBAF [n-Bu₄NF] led to the corresponding allenylphosphonate; in contrast, the use of CsF in a similar reaction led to novel γ-diiodo-allenylphosphonate along with the corresponding non-halogenated allenylphosphonate. The combination AgF₂/CuBr could be used to obtain the γ-fluoro-β-iodo-vinyl phosphine oxides and related phosphorus-free γ-fluoro-β-iodo-vinyl esters. In many cases, I⋯O halogen to oxygen non-covalent bonding interactions (‘halogen bonding’) involving the phosphoryl (PO) oxygen, as evidenced by single crystal X-ray crystallography, are also observed.