Novel synthetic route for (parent) phosphetanes, phospholanes, phosphinanes and phosphepanes

Abstract

A novel synthetic route for (parent) phosphorus-containing cycloalkanes such as phosphetanes, phospholanes, phosphinanes and phosphepanes is reported. By using [K(dme)₂]₂[Cp*Fe(η⁴-P₅)] (I) in combination with α,ω-dibromoalkanes C_nH_2nBr₂ [n = 3–6], unique phosphetane, phospholane, phosphinane and phosphepane precursor complexes [Cp*Fe{η⁴-P₅(CH₂)_n}] [n = 3–6] (2–5) are synthesised. They act as P-atom carriers and the corresponding phosphetane, phospholane, phosphinane and phosphepanes (6–9) can be released by nucleophiles i.e., potassium benzyl (KBn) or LiAlH₄. The latter enables the selective synthesis of parent cyclic secondary phosphines (10) in an easy and straightforward way, including the first parent phospholane (10b).