Our group recently published a new article titled “Tris(benzophenoneimino)phosphane and Related Compounds” led by Marta and Agnes.
In this work, a new group of bases with benzophenoneiminyl (bpi) moiety was synthesized and characterized. A convenient one-pot approach was employed to synthesize the starting compound tris(benzophenoneimino)phosphane (P(bpi)3): benzophenone imine was deprotonated using MeMgCl, followed by its reaction with PBr3 in diglyme. This method offers an alternative for preparing other (amino)phosphanes as well when lithio-intermediates and/or protonated phosphanes are not viable options. P(bpi)3 was subsequently utilized to synthesize a variety of related phosphonium cations and phosphazenes.
The stability of the resulting phosphonium ylides was assessed through their deprotonation. In certain cases, the bulky substances demonstrated the ability to form P-N heterocycles with adjacent P and N atoms and P=C double bonds which are quite rare and only some representatives of this type of heterocycles have been reported before. The basicities of benzophenone imine, P(bpi)3, phosphonium ylides, and phosphazenes were evaluated experimentally (in MeCN) or computationally (in MeCN, THF, and gas-phase). Additionally, representative X-ray crystallography (XRD) structures were presented and discussed. Although the bpi-compounds are not as strong as many existing bases, they still exhibit considerable basicity and could be employed as reagents to overcome common challenges such as solubility, ion-pairing, lack of UV-Vis properties, and other issues.