Regio- and Stereoselective Hydrophosphorylation of Ynamides for the Synthesis of β-Aminovinylphosphine Oxides

Abstract

A metal-free hydrophosphorylation of ynamides with diaryl phosphine oxides has been developed. A highly E-selective and β-regioselective hydrophosphorylation protocol has been established as a general method for the synthesis of diversely hydrophosphinylated products employing an in situ generated electrophilic phosphorus species. Deuterium incorporation experiments suggest that the amino phosphirenium intermediate undergoes a concerted ring-opening hydrolysis upon treatment with HO to exclusively furnish β-aminovinylphosphine oxides.

Regio‐ and Stereoselective Hydrophosphorylation of Ynamides: A Facile Approach to (Z)‐β‐Phosphor‐Enamides

“…In addition, Yamagishi and co‐workers realized the regio‐ and stereoselective hydrophosphorylation of terminal ynamides by employing a copper catalyst (Figure , eq b) . Very recently, Kang group developed a metal‐free hydrophosphorylation of ynamides with diaryl phosphine oxides for the synthesis of β ‐phosphor‐enamides (Figure , eq c) . It is noted that only ( E )‐ β ‐phosphor‐enamides were obtained with cis ‐addition of the electrophiles in all these cases.…”

“…[14] Evano reported the nickel-catalyzed hydrophosphorylation of internal ynamides with dialkyl phosphites to furnish β-phosphorenamides with excellent regio-and stereoselectivity ( Figure 2, eq b). [17] It is noted that only (E)-β-phosphor-enamides were obtained with cis-addition of the electrophiles in all these cases. [16] Very recently, Kang group developed a metal-free hydrophosphorylation of ynamides with diaryl phosphine oxides for the synthesis of β-phosphor-enamides (Figure 2, eq c).…”

Triflic Anhydride (Tf2O)-Activated Transformations of Amides, Sulfoxides and Phosphorus Oxides via Nucleophilic Trapping

“…In 2018, our group applied electrophilic P-species derived from diarylphosphine oxides and Tf 2 O to a metal-free hydrophosphorylation of ynamides 64a to generate -aminovinylphosphine oxides 64b (Scheme 64). 110 Aryl-or alkyl-substituted alkynes afforded the target products 64c and 64d with high yields of 91% and 95%, respectively. The steric demand on an alkyne with an oxazolidine-2-one motif was also well tolerated by providing the corresponding product 64e in 83% yield.…”

Phospha-Michael reaction of tertiary phosphanes Ph2P–X (X=SiMe3, Cl) and N-triflyl-propiolamides

“…Thus, the hydrophosphorylation of diphenylacetylene was achieved with Ph 2 P-Cl in the presence of AlCl 3 [23], or with a reagent generated in situ from diphenylphosphane oxide (Ph 2 P(=O)H), Tf 2 O and 2,6-lutidine [24]. The latter reagent also allowed the highly regioselective hydrophosphorylation of N-acyl-and N-sulfonyl-ynamides (R-C≡C-N(R′)-EWG) [25]. In all three cases, a phosphirenium ion was postulated as an intermediate and detected by 31 P NMR spectroscopy.…”