Fluoride-mediated phosphinations

Reprinted from M. Hayashi, Y. Matsuura, Y. Watanabe, Fluoride-mediated phosphination of alkenes and alkynes by silylphosphines, Tetrahedron Letters, 45, 9167-9169. Copyright (2004), with permission from Elsevier. 

On the synthetic side, single diastereomers of P-keto phosphine oxides have been generated from intermolecular acylation of phosphine oxides using either chiral esters or chiral phosphine oxides. In most cases, reduction of the ketone products was not affected by the presence of extra chiral centres. Addition of metallated phosphine oxides to proline-derived ketoaminals provides a new route to optically active P-hydroxy phosphine oxides. The P-hydroxy phosphine oxide 97 has been prepared by the caesium fluoride mediated reaction of silyl-substituted phosphine oxide 98 and benzaldehyde." The synthesis of two (E)-(6-hydroxy-2-hexen-l-yl)diphenylphosphine oxides (99) has been reported. The Horner-Wittig reactions of these compounds with various carbonyl compounds... 

Tris(TMS)phosphine also undergoes arylation reactions with suitably activated aryl halides. Thus, tris-2-pyrimidinylphosphine can be obtained via fluoride-mediated trisarylation with 2-chloro-pyrimidine (eq 7). ... 

In 1998, Carreira reported that a catalyst formed from Tol-BINAP, Cu(OTf)2, and 2 equiv of Bu4N+ Ph3SiF2 (TBAT), a soluble fluoride source, was extremely effective in mediating the aldol reaction between a silyldienolate and aromatic or vinyl aldehydes (254). Although initially formulated as a Cu(II) catalyst, subsequent evidence has shown that the active catalyst is a Cu(I) phosphine complex. By using only 2 mol% of the complex, excellent yields and enantioselectivities are observed with a range of aromatic aldehydes (93-95% ee, 86-98% yield), along with some enals (cinnamaldehyde provided the aldol adduct in 83% yield and 85% ee), Eq. 221. 

BF3 Et20 has been shown to mediate and catalyze the substitution of ferf-alkyl fluorides with various nucleophiles including silyl enol ethers, allyl silanes, hydrosilanes and phosphines (eq 53). 5... 

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