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Download fileReactions of Tri-tert-Butylphosphatetrahedrane as a Spring-Loaded Phosphinidene Synthon Featuring Nickel-Catalyzed Transfer to Unactivated Alkenes
journal contribution
posted on 2022-04-19, 21:08 authored by Martin-Louis
Y. Riu, André K. Eckhardt, Christopher C. CumminsCage-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 [tBu3C3]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.
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wittig reagent phunactivated alkenes cagestabilized silylene ledred crystalline solidgenerated phosphaalkene intermediatederived phosphirane productcomputational studies suggest51 – 64[< sup ><nickel phosphinidene speciescatalyzed phosphinidene transfer2 subisolated yield ).3 sub1 bphosphinidene transfercatalyzed transfer> sup2 equivtert tri -<protecting groupnmr spectroscopycorresponding phosphiranescorresponding phosphasilenealso observed>- butylphosphatetrahedrane