Formula C47H46O2P2 | ||
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SPANphos is an organophosphorus compound used as a ligand in organometallic and coordination chemistry. This compound is a rare example of a trans-spanning ligand and rigidly links mutually trans coordination sites. By virtue of its chiral backbone that forms a chiral cavity over the face of a square planar complexes, e.g. in MCl2(SPANphos) (M = Pd, Pt).
Synthesis
This C2-symmetric trans-diphosphine is synthesized from inexpensive reagents. In the first step 4,4,4',4',6,6'-hexamethyl-2,2'-spirobichroman is prepared via an acid-catalyzed reaction between p-cresol and acetone. The spirane is brominated with N-bromosuccinimide, and the resulting dibromide is metalated with n-BuLi. Treatment of the resulting dilithio derivative with chlorodiphenylphosphine completes the synthesis.