Homoannular Double Friedel–Crafts Acylation of Phosphametallocenes

Two reaction modes of homoannular double Friedel–Crafts acylation are realized using polyalkylphosphametallocenes as substrates. The first example is the reaction of tetra(tert-butyl)diphospharuthenocene with excess acetyl chloride/aluminum chloride, giving a 2,3-double Friedel–Crafts acylation product with an elimination of one of the tert-butyl groups. The other is the 2,5-diacylation of 1′,2′,3,3′,4,4′,5′-Me7-phosphaferrocene using an acyl chloride/aluminum chloride mixture. These reactions provide rare examples of doubly functionalized phosphametallocenes.