Derivatives of acetamide containing difluorophosphino-groups

Abstract

Bis(trimethylsilyl)acetamide reacts with an equimolar proportion of PF₂Br at –80 °C to give CH₃C(OSiMe₃):NPF₂. With an excess of PF₂Br, the initial product at –80 °C is CH₃C(OPF₂):NPF₂; at temperatures above –40 °C there is a slow rearrangement to give a mixture of CH₃C(OPF₂):NPF₂ and CH₃CON(PF₂)₂. All these PF₂ derivatives of acetamide decompose slowly at room temperature to give acetonitrile and either PF₂OSiMe₃ or (PF₂)₂O. They have been characterised by ¹H, ¹⁹F, and ³¹P n.m.r. and by i.r. spectroscopy. There was no evidence for fast exchange of PF₂ groups between N and O sites.