Synthesis and reactivity of P-acetylenic (silylamino)phosphines

The title compounds, (Me3Si)2NP(CCR)2 (1: R=SiMe3; 2: R=n-Bu; 3: R=CH2OCH3), (Me3Si)2NP(Ph)CCSiMe3 (4), and (Me3Si)2NP(R)CCCH2OCH3 (5: R=i-Pr; 6: R=CH2SiMe3; 7: R=n-Bu) were obtained from the reactions of C-lithiated acetylenes LiCCR with either mono- or dichloro substituted (silylamino)phosphines. Similar reactions involving HCCMgCl gave the parent P-ethynyl derivatives, (Me3Si)2NP(R)CCH (12: R=CH2SiMe3; 13: R=Ph). Deprotonation–substitution at the terminal CH group of 12 readily afforded the Me3Si derivative, (Me3Si)2NP(CH2SiMe3)CCSiMe3 (14). Oxidative bromination of 7 gave the P-bromophosphoranimine, Me3SiNP(n-Bu)(CCCH2OCH3)Br (8). The P-trifluoroethoxy analogs, Me3SiNP(CH2SiMe3)(CCCH2OCH3)OCH2CF3 (10) and Me3SiNP(CCSiMe3)2OCH2CF3 (11), were prepared from phosphines 6 and 1, respectively, via bromination followed by substitution with CF3CH2OH–Et3N. The diphosphinoacetylenes, (Me3Si)2N(R)PCCP(R)N(SiMe3)2 (15: R=n-Pr; 16: R=CH2SiMe3), were obtained by treating appropriate P-chloro(silylamino)phosphines with the carbide reagent LiCCMgCl. All of these P-acetylenic derivatives were thermally stable, distillable liquids that were characterized by NMR spectroscopy.