The ability of the β-CH functionality in a butylmagnesium cation [Me6TREN-Mg-n-Bu]+ to quantitatively reduce benzophenone has been demonstrated. The hydridic nature of the β-CH functionality is highlighted by its abstraction using B(C6F5)3. β-CH abstraction over alkylation in [Me6TREN-Mg-n-Bu]+ is dependent on the nature of the incoming electrophile and the polarity of the solvent.

The sterically hindered monomeric alkoxomagnesium compound [(Me 6 TREN)MgOCHPh 2 ][B(C 6 F 5 ) 4 ] (1) has been used to explore the role of magnesium alkoxides in ketone hydroboration. Experiments and DFT calculations are suggestive of a concerted reaction pathway traversing through a six-membered transition state involving MgÀ OCHPh 2 , BÀ H, and C=O bonds. Prompted by this hypothesis, we investigated the activity of [Mg(OCHPh 2 ) 2 ] (3), which exhibits turn-over frequency reaching up to 59,400 h À 1 under solvent-free conditions and stability towards C=C, À OH, À NH 2 and À NO 2 . Due to the non-existence of a metal hydride intermediate, such catalytic reactions will not get hindered in the presence of additional reactive functional groups.

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We present the reactivity of the Mg-C and the β-CH bonds in the trigonal pyramidal [(pmdta)Mg(nBu)]+ exhibiting a weak Mg···F interaction with counter anion, [B(C6F5)4]-. Instantaneous β-hydride reactivity with benzophenone,...

The Cover Feature shows a concerted carbonyl hydroboration mechanism involving Mg−O, B−H, and C=O bonds. Homoleptic magnesium alkoxides catalyze ketone hydroboration with a turn‐over frequency (TOF) reaching up to 59,400 h−1 and exhibit exceptional functional group tolerance. This TOF is so far the best observed in a main group catalyst without the involvement of a metal hydride intermediate. The newly proposed mechanism finds general applicability in magnesium alkoxides and stimulates interest in exploring other metal alkoxides in reduction chemistry. More information can be found in the Full Paper by L. Maron, A. Venugopal and co‐workers.