Electroreduction of tetra-coordinate phosphonium derivatives; one-pot transformation of triphenylphosphine oxide into triphenylphosphine

Rasta Resin–PPh3–NBniPr2 and its Use in One‐Pot Wittig Reaction Cascades

“…The first stage of regenerating 3 involved phosphine oxide reduction, and the second was ammonium salt deprotonation. While numerous methods for phosphine oxide reduction have been reported in the literature, [17][18][19] we chose to use trichlorosilane and N,N-dimethylaniline in refluxing 1,4-dioxane for this purpose; for the deprotonation operation we used an excess of NiPr 2 Et. The completion of the reduction of 10 was determined by gel-phase 31 P NMR spectroscopic analysis, while the success of its deprotonation was determined empirically by the successful use of regenerated 3 in a subsequent Wittig reaction cycle (see below).…”

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…861 The same group also investigated the reduction of triphenylphosphine dichloride and methoxytriphenylphosphonium triflate (Figure 48E, left). 862,863 …”

Catalytic Wittig and aza-Wittig reactions

“…In this regard it is encouraging that a life cycle assessment indicates that the use of stoichiometric quantities of silanes as replacements for phosphines in catalytic Wittig reactions can offer environmental improvements [41]. Thus it seems somewhat reasonable to expect that as even more efficient methods for phosphine oxide reduction are discovered [42–47], catalytic reactions involving cycling between phosphines and phosphine oxides will become more environmentally friendly and more popular too. With regards to the phosphine oxide-catalyzed aza-Wittig reactions discussed, while no life cycle assessments have been performed, they do seem to be rather “green” since no redox cycling is necessary, and there appear to be few constraints to their potential application.…”