190847-68-8Relevant academic research and scientific papers
The role of lithium 1,3-bis(trimethylsilyl)-1-aza-allyls in phosphorus chemistry
Hitchcock, Peter B.,Lappert, Michael F.,Layh, Marcus
, p. 386 - 398 (2007/10/03)
Treatment of the lithium 1-aza-allyl [Li{N(R)C(tBu)CHR}]2 1, abbreviated as [Li(LL′)]2, with PCl3 gave in poor yields the trans-P,P′-dichlorodiazaphosphetidine ClPN(R′)P(Cl)NR′ 3 (R = SiMe3, R′ = C(tBu)=C(H)SiMe3). An improved route to 3 was based on [{Cu(μ - LL′)}2] and PCl3. However, the method of choice involved conversion of 1 into successively the imine RN=C(tBu)CHR2 4 (which upon heating gave the isomeric enamine 5) and Cl2PN=C(tBu)CHR2 6 and thermolysis of 6. The imine RN=C(tBu)CH(R)PPh2 7, obtained from [Li(LL′)]2 1 and Ph2PCl, was isomerised into the Z-enamine R2NC(tBu)=C(H)PPh2 8, which upon irradiation gave a mixture of 8 and its E-isomer 9. Treatment of 7 with R″PCl2 or PCl3 gave the cyclic phosphonium chlorides [Ph2PP(R″)N(H)C(tBu)=CH]Cl (10 R″ = Ph, or 11 R″ = Et) or [Ph2PP(Cl)N(R)C(tBu)=CH]Cl 12; 12 with AgOSO2CF3 or Na[BPh4] afforded [Ph2PP(Cl)N(R)C(tBu)=CH]A (13 A = CF3SO3, or 14 A = BPh4). The enamines RN=C(tBu)CH(X)R (15 X = Cl, or 16 X = I) were obtained from 1 and POCl3 or ICl, respectively, and the enamine R2NC(Ph)=CR2 17 was obtained from the lithium 1-aza-allyl [Li{N(R)C(Ph)CR2}(THF)] and CF3SO3SiMe3. Compounds 3-17 were characterised by multinuclear NMR spectroscopy and (in most cases) MS, while single crystal X-ray diffraction data are provided for 3 and 10.
