Reactions of Tri-tert-Butylphosphatetrahedrane as a Spring-Loaded Phosphinidene Synthon Featuring Nickel-Catalyzed Transfer to Unactivated Alkenes

Abstract

Cage-opening reactions of the highly strained tri-tert-butylphosphatetrahedrane (1), shown here to function as a synthon of (tri-tert-butylcyclopropenyl)­phosphinidene, are described. Treatment of 1 with a base-stabilized silylene led to the corresponding phosphasilene, which was isolated in 72% yield as a red crystalline solid. Phosphinidene transfer was also observed when 1 (2 equiv) was combined with the Wittig reagent Ph3PCH2 to form a diphosphirane (50% isolated yield). The reaction is proposed to proceed through a generated phosphaalkene intermediate, which was characterized by NMR spectroscopy. In addition, we report on nickel-catalyzed phosphinidene transfer to styrene, ethylene, neohexene, and 1,3-cyclohexadiene; the corresponding phosphiranes were isolated in 51–64% yield. Computational studies suggest the intermediacy of a nickel phosphinidene species. Treatment of the ethylene-derived phosphirane product with triflic acid delivered elimination of [ t Bu3C3]­OTf and formation of a P–H bond, illustrating the ability of the tri-tert-butyl cyclopropenyl group to serve as a protecting group that is removable following phosphinidene transfer.

On the Reactivity of Phosphaalumenes towards C−C Multiple Bonds

“…(tBuC) 3 PCH(Ph)CH 2 δ( 31 P) = À 170.4 ppm). [36] Evaporation of the solvent and recrystallization from a saturated n-pentane solution at À 30 °C afforded crystals for SC-XRD experiments and the formation of bicyclic compound 11 (Figure 7), containing both a cycloaluminapentane and phosphirane unit was confirmed. The five-membered cycloaluminapentane unit is minimally folded along the C3À C6 axis (16.7(2) °) and the plane of the three-membered phosphirane-ring is bend away from the planar C3À C4À C5À C6 unit by 109.49(18) °.…”

Novel synthetic route for (parent) phosphetanes, phospholanes, phosphinanes and phosphepanes

“…14,15 Very recently, Cummins reported the synthesis of the parent phosphirane (C 2 H 5 P), not coordinated to W(CO) 5 , 16 based on a multistep Nickel-catalysed transfer reaction of tri-tert-butylphosphatetrahedrane. 17 Other parent phosphorus-containing heterocycles are usually accessible by low yields, time-consuming synthesis or less selective methods. 18,19 Specically, secondary cyclic phosphines are prepared by hydrolysis of silylated species or protonation of suitable precursors.…”

“…18,19 Specically, secondary cyclic phosphines are prepared by hydrolysis of silylated species or protonation of suitable precursors. 17,20,21 However, the latter usually also have to be synthesised in a complex manner, using rather unselective conventional routes with low overall yields. 20,21 Therefore, there is an increasing need for a rational and direct synthesis of cyclic phosphines, especially of the parent derivatives (Scheme 1).…”

Über die Reaktivität von Phosphaalumenen gegenüber C−C‐Mehrfachbindungen

“…( 31 P) = À 7.9 ppm, δ ber. ( 31 P) = À 1.4 ppm) [20] [36] Nach Verdampfen des Lösungsmittels und Umkristallisieren aus einer gesättigten n-Pentanlösung bei À 30 Basis von P und Al sind von besonderem Interesse und die Pionierarbeiten von Zargarian haben den Weg für die Anwendung von P/Al-FLPs in einer Vielzahl von stöchiometrischen und katalytischen Aktivierungsreaktionen von kleinen Molekülen geebnet. [37] Mechanistisch gesehen könnte die Bildung von 11 über zwei Routen erfolgen, jedoch kann die anfängliche Bildung eines Aluminacyclopentens in einer [4+1]-Cycloaddition, an der nur Cp*Al beteiligt ist, wie von Crimmin und Mitarbeitern berichtet, [38] die dann mit dem freien Phosphiniden Dip TerP in einer [2+1]-Cycloaddition reagiert, aufgrund experimenteller Beobachtungen ausgeschlossen werden.…”