Phosphaketenes as building blocks for the synthesis of triphospha heterocycles

Heift, Dominikus, Benkő, Zoltán and Grützmacher, Hansjörg (2014) Phosphaketenes as building blocks for the synthesis of triphospha heterocycles. Chemistry - A European Journal, 20(36), pp. 11326-11330. ISSN (print) 0947-6539


Unsaturated phosphorus compounds, such as phosphaalkenes and phosphaalkynes, show a versatile reactivity in cycloadditions. Although phosphaketenes (R-P=C=O) have been known for three decades, their chemistry has remained limited. Herein, we show that heteroatom-substituted phosphaketenes, R(3) E-P=C=O (E=Si, Sn), are building blocks for silyl- and stannyl-substituted five-membered heterocycles containing three phosphorous atoms. The structure of the heterocyclic anion depends on the nature of the tetrel atom involved. Although the silyl analogue [P(3)C(2) (OSiR(3))(2)](-) is an aromatic 1,2,4-triphospholide, the stannyl compound [P(CO)(2) (PSnR(3))(2)](-) is a 1,2,4-triphosphacyclopenta-3,5-dionate with a delocalized OCPCO fragment. Because of their anionic character, these compounds can easily be used as building blocks, for example, in the preparation of a silyl-functionalized hexaphosphaferrocene or the parent 1,2,4-triphosphacyclopenta-3,5-dionate [P(CO)(2) (PH)(2)](-). NMR spectroscopic investigations and computations have shown that the heterocycle-formation reactions presented herein are remarkably complex.

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