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Secondary phosphine oxides reacted with 1-alkanoyl-2-phenylacetylenes in chemoselective fashion under mild conditions (20°C, THF) in the absence of a catalyst (diphenylphosphine oxide) or in the presence of potassium hydroxide [bis(2-phenylethyl)phosphine oxide] to give 1-alkyl-1-diphenyl(or 2-phenylethyl)-phosphoryl-3-phenylprop-2-yn-1-ols in up to 96% yield. The reaction of diphenylphosphine oxide with 1-alkanoyl-2-phenylacetylenes in the system KOH-THF (20°C) afforded not only adducts at the carbonyl group but also products of double α,β-addition at the triple bond, 2,3-bis(diphenylphosphoryl)-3-phenylpropan-1-ones.

Durch Reaktion der Acetylenketone (I), die über eine aktivierte Acetylenfunktion verfügen, mit Dithiobiuret im Molverhältnis 4:1 werden die Bis‐ketovinylsulfide (IIIa) bzw. (IIIb) als E/E‐,E/Z‐ und Z,Z‐Gemische erhalten.

The reaction of tri(2‐pyridyl)phosphine with electron‐deficient alkynes in water proceeds under mild conditions (40–45 °C, without catalyst, 4–5 h) with liberation of pyridine to give (E)‐pyridylvinylphosphine oxides in 45–56 % yields, the only exception being the reaction with cyanophenylacetylene, which affords the corresponding vinylphosphine oxide of Z‐configuration in 40 % yield. The reaction is likely triggered by the zwitterion, the adduct of tri(2‐pyridyl)phosphine to the electrophilic acetylenes, the carbanionic center of which is then neutralized by a proton from water. The intermediate phosphonium hydroxide finally decomposes to the product.