Synthesis of Benzene Derivatives with Multiple Dichlorophosphino Groups

The synthesis of benzene derivatives with multiple PCl₂ groups, starting from the corresponding phosphanes by chlorination with PCl₅ is reported in this work. The synthesised 1,2-bis(dichlorophosphino)benzene, 1,2,4-tris(dichlorophosphino)benzene and 1,2,4,5-tetrakis(dichlorophosphino)benzene were isolated in excellent yields ≥89 %. The follow up chemistry towards primary amines is also described.

Abstract

The chlorination of 1,2-diphosphinobenzene with PCl₅ to 1,2-bis(dichlorophosphino)benzene was performed with high yields (93 %) despite the high number of P−H functions. The method was further applied to other phosphanes, enabling the first synthesis and complete characterization of 1,2,4-tris(dichlorophosphino)benzene (89 % yield) and 1,2,4,5-tetrakis(dichlorophosphino)benzene (91 % yield), valuable precursors for example for binuclear complexes, coordination polymers, organic wires, or metal–organic frameworks. The application of the chlorophosphanes in base induced ring closure reactions with primary amines is demonstrated.

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