Regioselective addition of secondary phosphine oxides to 3-(trialkylsilyl)- and 3-(trialkylgermyl)-2-propynals

Group 10 Metal Complexes of SPS‐Based Pincer Ligands: Syntheses, X‐ray Structures, and DFT Calculations

“…[26] Interestingly, 5 could also be used as a source of [Pd(SPSOH)Cl] (6) [SPS ϭ C 5 H(Ph 2 PS) 2 P] upon reaction with [Pd(COD)Cl 2 ] (Scheme 3). Scheme 3 Complex 6 was characterized by 31 P and 1 H NMR as well as by elemental data but was too insoluble to be characterized by 13 C NMR spectroscopy. Fortunately, suitable crystals for an X-ray crystal analysis could be grown by diffusing hexanes into a chloroform solution of the complex.…”

“…It is relatively difficult to propose a definitive mechanism to account for the formation of 6 from 5. Indeed, 31 P NMR monitoring of the reaction revealed only signals corresponding to 5 and 6. Two possible mechanisms leading to 6 can be proposed, both of which are promoted by the initial displacement of the COD ligand by the two ancillary phosphane sulfide groups to yield an intermediary PdCl 2 complex.…”

“…Since no intermediates could be detected in 31 P NMR spectroscopy during the synthesis of 10 and 11, no definitive mechanism can be proposed. However, a mechanism close to that proposed for the synthesis of complex 6 seems plausible.…”

“…Thus, complex 13 was easily obtained by treating (Ϫ)-menthol with 2 in dichloromethane at room temperature. The formation of 13 was evidenced by an ABC spin system pattern in 31 P NMR spectrum Ϫ a result of the chiral group introduced at phosphorus, which renders the two ancillary PPh 2 S substituents magnetically non-equivalent (see Exp. Sect.).…”

Nucleophilic and free-radical additions of phosphines and phosphine chalcogenides to alkenes and alkynes

“…α,β-Acetylenic aldehydes, namely 3-(trialkylsilyl)-, 3-(trialkylgermyl)-2-propynals as well as 2-propynal react with secondary phosphine oxides under mild conditions (-10 to 22 o C) by carbonyl group only to give corresponding tertiary phosphine oxides in quantitative yield. 166 Haloacetylenes are usually prone to nucleophilic substitution reactions. [167][168][169] However, bis(2-phenylethyl)phosphine oxide (5a) was found to add to alkylthio(chloro)acetylenes (dioxane, 20-22 o C) in the presence of equimolar amount of KOH to form regio-and stereoselectively 1-chloro-2-(alkylthio)vinyl(diphenylethyl)phosphine oxides (38) (Scheme 27) of Z-configuration (the yield is 78-85%).…”