Solid state reactions of organopentafluorosilicates with copper(I) and copper(II) salts

Practical and scalable synthesis of bench-stable organofluorosilicate salts

Silanes have enjoyed significant success as synthetic tools in the last few decades. In many of the reactions that use silanes, a pentacoordinate silicate is proposed as the reactive intermediate. Despite this, there is no general method to synthesize pentacoordinate fluorosilicates and use them as reagents instead of organo- or alkoxysilanes. Herein, we report the first practical synthesis of organotetrafluorosilicates. The method is tolerant of a number of different functional groups including electrophiles with preferential attack of the fluoride on the silane rather than the electrophile. This transformaton is generally high yielding, even at the mole scale. Furthermore, we demonstrate that organotetrafluorosilicates are both more reactive than the corresponding trialkoxysilanes and more stable under solvolytic conditions. Organotetrafluorosilicates can be used as substrates for a variety of coupling reactions, oxidations, and radical reactions. Overall, organotetrafluorosilicates represent a new platform on which to develop challenging transformations.

Nucleophilic Activation of Alkenyl and Aryl Boronates by a Chiral CuIF Complex: Catalytic Enantioselective Alkenylation and Arylation of Aldehydes

A new method for the catalytic enantioselective alkenylation and arylation of aldehydes involves the activation of alkenyl and aryl boronates by a catalytic amount of the Cu(I)F-DTBM-segphos complex through transmetalation, generating novel alkenyl and aryl copper species. These reagents act as the actual nucleophile. A range of aldehydes can be converted into optically active secondary allyl alcohols or diaryl methanols with excellent enantioselectivity. The appropriate choice of additives, depending on the substrate, is critical to ensure high yields of products. These additives possibly modulate the catalyst turnover step from copper alkoxide intermediates generated by the addition of organocopper reagents to aldehydes.