Synthese und Struktur von 1,4‐Dihydro‐1,4‐diphosphininen und 1,4‐Dihydro‐1,4‐phospharsininen

Abstract

Synthesis and Structure of I&Dihydro-l,4diphosphinines and 1,CDihydro-1,CphospharsininesThe cyclizing addition of phenylphosphane or phenylarsane to tert-butyl(benzy1, diethylamin0)diethinylphosphane (14) with formation of the 1,4-dihydro-1 +diphosphinines*' 11 a -d and 1,4-dihydro-1,4-phospharsinines 12a -d, resp., occurs by a radical mechanism (AIBN) as well as base-catalyzed (NaNH,/NH,l; KOH/[18]-crown-6); 11 and 12 are formed as mixtures of cisltrans-isomers with the cis-isomers with (e,e)-conformation prevailling. This is confirmed by X-ray analysis of l-tert-butyl-l,4-dihydro-4-phenyl-l,4-diphosphinine (11 a). The cyclizing addition of primary alkylphosphanes (tert-butylphosphane, benzylphosphane) to diethinylphosphanes is possible only by KOH/[18]-crown-6 catalysis (11 e-f). -A NOEDS-study of l-benzyl-4-tert-butyl-1,4-dihydro-l,4-diphosphinine (11 e) confirms the assigned cis(e,e)-structure. 1,4-Dibenzyl-l,4-dihydro-1,4-diphosphinine (11 g) cannot bc isolated, following reactions via the 1,4-diphosphinine arc discusscd. Only by base-catalyzed (NaNH2/NH31; KOH/[18]-crown-6) cyclizing addition of aryl-, alkylphosphanes, and phenylarsane to di-1-propinylphosphane the 1,4-dihydro-3,5-dimethyl-1,4-di-*I Phosphorine heiDen nach den neuen IUPAC-Regeln (W. H . Powell, Pure Appl. Chem.55, 40Y (1983)) Phosphinine.

Synthesis, Substitution, and Oxidation of Imidazole‐2‐thione Based Tricyclic 1,4‐Dihydro‐1,4‐diphosphinines

“…Later on, Uchida added a further simplification to the synthetic protocol of IIb . The synthesis of I was achieved by Märkl by the reaction of diethynylphosphane with a primary phosphane, which led to new P‐substituted derivatives. The idea of replacing the benzannulated units in II by other rings led to other tricycles with tetrafluoro‐benzene, thiophene, xylene, and tetrathiafulvalene ring systems.…”

“…Similarly, compound IV was obtained by the thermal reaction of the corresponding backbone, dichlorophosphanyl‐substituted 1‐methyl‐2‐alkyl‐imidazole, with pyridine (as the base), thus leading to the tricyclic heterocyclic scaffold shown in Figure . Hitherto, surprisingly few reactivity studies have been reported on mono‐, bi‐, or tricyclic 1,4‐dihydro‐1,4‐diphosphinines relying exclusively on derivatives possessing exocyclic P–C single bonds,, thus significantly restricting the opportunities of P functionalization.…”

The Quest for Twofold Reductive P–C Bond Cleavage of P–Ph Substituted 1,4‐Dihydro‐1,4‐diphosphinine Derivatives

“…The 1,4‐dihydro‐1,4‐diphosphinines, though well‐known since 1964, reactivity studies have received little attention. Recently, we reported on a new class of imidazole‐2‐thione‐based tricyclic 1,4‐dihydro‐1,4‐diphosphinines and their conversion into 1,4‐diphosphinines using dedichlorination under mild conditions .…”

Synthesis and Oxidation Reactions of Thiazol‐2‐thione‐fused 1,4‐Dihydro‐1,4‐diphosphinines

“…[2] The parent compound (I) was reported by Märkl using double addition reaction of diethinylphosphanes and primary phosphanes leading to monocyclic 1,4-dihydro-1,4-diphosphinine derivatives having different P-substituents. [3] As it was shown later, other tricyclic systems than II having (unsubstituted) annulated benzene rings could be accessed, i. e., tetrafluorobenzene [4] and xylene, [5] could be incorporated as reported by Wu and Mazaki, respectively. [4][5] This could be expanded further to compounds III-V ( Figure 1) representing examples of S-heterocycles being annulated to the 1,4-dihydro-1,4-diphosphinine ring, i. e., thiophene (III), [6] tetrathiafulvalene (TTF) (IV) [7] and 2,5-thiophene-dione (V, E = S).…”

“…Later, this was improved by Uchi da and co‐workers who also investigated structural and electron donor properties of II . The parent compound ( I ) was reported by Märkl using double addition reaction of diethinylphosphanes and primary phosphanes leading to monocyclic 1,4‐dihydro‐1,4‐diphosphinine derivatives having different P ‐substituents . As it was shown later, other tricyclic systems than II having (unsubstituted) annulated benzene rings could be accessed, i .…”