Synthesis and reactivity of some p-mesityl-substituted phosphorus compounds

Abstract

Abstract : The preparation and characterization of a series of P-mesityl substituted phosphorus compounds containing the Si-N-P and/or Si-C-P linkages are described. The reaction of RPC12 (R = 2,4,60Me3C6H2) with one equivalent of (Me3Si)2NLi affords the thermally unstable chlorophosphine (Me3Si)2NP(R)Cl (compound 1) in nearly quantitative yield. Substitution reactions of compound 1 are used to prepare the stable derivatives (Me3Si)2NP(R)X (compound 2, X = Me; compound 3, X = H; compound 4, X = CH2SiMe3), while treatment with Me3SiN3 yields the unstable axidophosphine (Me3Si)2NP(R)N3 (compound 5). The methylphosphine compound reacts smoothly with CC14 via elimination of CHCl3 with a (1,3)-silyl shift to form the chlorophosphinimine Me3SiN=P(R) (CH2SiMe3)Cl (compound 6), which is readily converted to the P-Me analogue compound 7 by reaction with MeLi. Depending on the reaction stoichiometry, treatment of RPCl2 with Me3SiCH2MgCl gives either the chlorophosphine Me3SiCH2P(R)Cl (compound 8) as an unstable product from which compound 4 is produced by reaction with (Me3Si)2NLi, or the stable disubstituted phosphine (Me3SiCH2)2PR (compound 9). Decomposition of the azidophosphine compound 5 proceeds with elimination of nitrogen and formation of the dimeric forms of the di(imino)phosphorane RP double bond(NSiMe3)2 (compound 5 a). Either the cis (compound 10) or trans (compound 11) four-membered ring dimer can be isolated under appropriate conditions. Proton, C(13), P(31) NMR data are reported for the new compounds. (Author)