Organophosphorus Compounds, 103. Thermal Transformation of Kinetically Stabilized Phosphaalkynes with Phosphinidene Precursors. Synthesis of Phosphorus‐Carbon Cage Compounds by Cocyclooligomerization Processes

Abstract

Abstract Phosphaalkynes 2 undergo cocyclooligomerization reactions with the phosphinidene 14 or the phosphinidene‐W(CO) 5 complex 18 to furnish the phosphorus‐carbon cage compounds 16 or 23. The phosphinidene 14 is generated by the thermal reaction of 2a‐c with the phosphole 11 , a process in which the initially formed 7‐phosphanorbornadienes 12a‐c decompose to the λ 3 ‐phosphinines 13a‐c and the desired reactive intermediate. When three further equivalents of the phosphaalkynes 2a‐c are employed, the tetraphosphahomoquadricyclanes 16a‐c can be isolated in 53‐65% yields. The second approach is based on the thermal fragmentation of 17 to generate the phosphinidene‐W(CO) 5 complex 18 which, in turn, reacts with four equivalents of the phosphaalkynes 2a or b to produce the pentaphosphadeltacyclanes 23a or b. The constitutions of these novel phosphorus‐carbon cage compounds were confirmed by X‐ray crystal structure analyses of 16a and 23a.