Manganese Ate Complexes as New Reducing Agents:  Perfectly Regiocontrolled Generation and Reactions of the Manganese Enolates with Electrophiles

Thermochemical Considerations of Metal Enolates

“…That manganese enjoys a variety of oxidation states means Mn(II) enolates may be obtained from ketones by deprotonation or from α-haloketones by redox reactions 224 ascribed to kinetic factors 225 , without thermochemical data on the relative stability of the two isomers. Mn(III) enolates are also known.…”

Manganese(ii): the black sheep of the organometallic family

“…46 Alkali metal manganates such as [R 3 Mn][Li] (R = n Bu, n Dec) (43a, 43b) are able to generate manganese enolates with a degree of regiocontrol directly from ketones bearing a leaving group in the a-position by acting as formal two-electron reducing agents (Scheme 18). 47 A mechanism was proposed to account for the generation of the manganese(IV) enolate ( 44) by oxidative addition of the ketone to 43b followed by reductive elimination to afford a manganese(II) enolate (45), which can then be used in aldol reactions and alkylations, the latter being specific for the monoalkylation product. A similar methodology has been applied to the generation of thiomethylmanganese(II) reagents, presumably of empirical formula '[PhSMn IV R 3 ]' (46), directly from the reaction between thiomethyl iodides and 43a, thus offering a useful alternative route to thiomethyl anions (Scheme 19).…”

Decarboxylative Oxyacyloxylation of Propiolic Acids: Construction of Alkynyl-Containing α-Acyloxy Ketones

“…α-Acyloxy ketone motifs widely exist in many natural products, synthetic drugs, and bioactive molecules . They also serve as versatile intermediates in organic synthesis, and widespread synthetic applications of α-acyloxy ketones in the construction of hydroxy ketones, diol derivatives, allylic esters, amino acyloxy compounds, heterocyclic aromatic scaffolds, and others have been demonstrated . In light of their importance, numerous methods for the synthesis of α-acyloxy ketones including the acetolysis of α-haloketones, insertion of α-diazoketones with carboxylic acids, direct oxidative coupling of ketones, and difunctionalization of alkenes or alkynes have been developed. , Despite these advances, developing an efficient method for the construction of α-acyloxy ketones is still in need.…”