Zirconium-Catalyzed Intermolecular Double Hydrophosphination of Alkynes with a Primary Phosphine

Abstract

Catalytic double hydrophosphination of internal alkynes and primary phosphines is possible using a zirconium complex, [κ5 -N,N,N,N,C-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH]Zr (1). The reaction proceeds via stepwise hydrophosphination to give vinyl phosphine products, which can be isolated or further converted to the respective 1,2-bis­(phosphino)­ethane (i.e., double hydrophosphination). The catalysis is highly selective for formation of secondary phosphine products.

Evidence for Iron‐Catalyzed α‐Phosphinidene Elimination with Phenylphosphine

“…With the success of trapping reactions with 2,3‐dimethyl‐1,3‐butadiene, more challenging substrates were attempted. Treatment of PhPH 2 with five equivalents of diphenylacetylene and 5 mol % of 1 gave double hydrophosphination of the alkyne in 42 % conversion with trace amounts of 1,2,3,4,5‐pentaphenylphosphole, as was measured by 31 P NMR spectroscopy . Formation of phosphole in greater than 10 % was achieved by running the same reaction under 1 atm of hydrogen.…”

Photocatalytic Hydrophosphination of Alkenes and Alkynes Using Diphenylphosphine and Triamidoamine‐Supported Zirconium

“…These reactions under extended periods provided exclusively the single P–H bond activation product, and none of the double hydrophosphination product was observed. In prior studies with 1 , double hydrophosphination has been observed for a primary phosphine substrate . These observations and prior reactivity of 1 suggest that the second hydrophosphination reaction is disfavored due to steric constraints and these reactions were not pursued further.…”

Iron(II)‐Catalyzed Hydrophosphination of Isocyanates

“…Theh ydrophosphination of olefins and alkynes has received much attention in the last decade, [4] but the use of heterocumulene substrates has been less explored, with examples of precatalysts for these reactions being limited to rare-earth, [5] alkali-metal, [6] and group 2c omplexes. [7] The hydrophosphination of organic isocyanates,yielding phosphinocarboxamide products,islimited to afew recent examples, all of which are catalyzed by f-block complexes.…”