Deoxygenation of isocyanates via transient electrophilic terminal phosphinidene complexes: Are strained P-heterocycles involved?

Synthesis of 1,4,2-Diazaphospholidine-3,5-diones Using Na(OCP) as the "P" Source

A refined synthesis of 1,4,2-diazaphospholidine-3,5-dione derivatives was achieved through a cyclization reaction involving Na(OCP) and isocyanates. Na(OCP) was demonstrated to be a relatively stable and safe source of phosphorus, enabling the production of diverse 1,4,2-diazaphospholidine-3,5-dione derivatives with high yields. The reaction proceeds efficiently under catalyst-free and mild conditions. Both experimental findings and density functional theory calculations have elucidated that the process involves a crucial step of carbon monoxide elimination, which provides deeper insight into the reaction mechanism.

1,2σ3λ3-Oxaphosphetanes and Their P-Chalcogenides-A Combined Experimental and Theoretical Study

Although 1,2σ⁵λ⁵-oxaphosphetanes have been known for a long time, the “low-coordinate” 1,2σ³λ³-oxaphosphetanes have only been known since their first synthesis in 2018 via decomplexation. Apart from ligation of this P-heterocycle to gold(I)chloride and the oxidation using ortho-chloranil, nothing on their chemistry has been reported so far. Herein, we describe the synthesis of new 1,2σ³λ³-oxaphosphetane complexes (3a–e) and free derivatives (4a–e), as well as reactions of 4a with chalcogens and/or chalcogen transfer reagents, which yielded the P-chalcogenides (14–16a; Ch = O, S, Se). We also report on the theoretical results of the reaction pathways of C-phenyl-substituted 1,2 σ³λ³-oxaphosphetanes and ring strain energies of 1,2σ⁴λ⁵-oxaphosphetane P-chalcogenides.

On 1,3-phosphaazaallenes and their diverse reactivity

1,3-Phosphaazaallenes are heteroallenes of the type RP Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CNR′ and little is known about their reactivity. In here we describe the straightforward synthesis of ArPCNR (Ar = Mes*, 2,4,6-tBu-C₆H₂; ^MesTer, 2.6-(2,4,6-Me₃C₆H₂)–C₆H₃; ^DipTer, 2.6-(2,6-iPr₂C₆H₂)–C₆H₃; R = tBu; Xyl, 2,6-Me₂C₆H₃) starting from phospha-Wittig reagents ArPPMe₃ and isonitriles CNR. It is further shown that ArPCNtBu are thermally labile with respect to the loss of iso-butene and it is shown that the cyanophosphines ArP(H)CN are synthetically feasible and form the corresponding phosphanitrilium borates with B(C₆F₅)₃, whereas deprotonation of ^DipTerP(H)CN was shown to give an isolable cyanidophosphide. Lastly, the reactivity of ArPCNR towards Pier's borane was investigated, showing hydroboration of the CN bond in Mes*PCNtBu to give a hetero-butadiene, while with ^DipTerPCNXyl the formation of the Lewis acid–base adduct with a B–P linkage was observed.

The combination of phospha-Wittig reagents with isonitriles affords 1,3-phosphaazaallenes and their diverse reactivity has been studied in detail.

"Low-coordinate" 1,2-oxaphosphetanes - a new opportunity in coordination and main group chemistry

While 1,2σ5λ5-oxaphosphetanes are well known intermediates from the Wittig-reaction, no 1,2σ3λ3-oxaphosphetanes have been described, so far. Herein, we present the first synthesis of 1,2σ3λ3-oxaphosphetanes derived from their κP-Mo(CO)5 complexes and first investigations towards metal coordination and P-oxidation. Bonding, ring strain energy and potential retro-[2+2] cycloaddition reactions of the 1,2-oxaphosphetane ring were studied by DFT methods.