Manganese‐Catalyzed Hydrogenation of Esters to Alcohols

Abstract

Homogeneous catalytic hydrogenation of esters to alcohols is an industrially important, environmentally benign reaction. While precious metal-based catalysts for this reaction are now well known, only very few catalysts based on first-row metal complexes were reported. Here we present the hydrogenation of esters catalyzed by a complex of earth-abundant manganese. The reaction proceeds under mild conditions and insight into the mechanism is provided based on an NMR study and the synthesis of novel Mn complexes postulated as intermediates.

Manganese Catalyzed Hydrogenation of Organic Carbonates to Methanol and Alcohols

“…[14] When ac atalytic reaction was performed under the conditions described for entry 2 ( Table 1) using the independently isolated complex 2,complete conversion of diethyl carbonate to ethanol and methanol in more than 90 %y ield was observed, indicating that complex 2 is an active catalytic species in the hydrogenation of carbonates.Inpresence of H 2 , complex 2 immediately forms the hydride complex 3 as previously reported by us. We have previously shown that complex 2 is an active catalyst for the hydrogenation of esters.…”

“…[14] Complex 1 was also used by us for the direct synthesis of cyclic imides by dehydrogenative coupling of diols and amines. [14] Complex 1 was also used by us for the direct synthesis of cyclic imides by dehydrogenative coupling of diols and amines.…”

“…[14] Theh ydride complex 3syn can be independently prepared in situ by the reaction of complex 1 with NaBEt 3 H. [14] Ther eaction of the in situ prepared complex 3 with 2-3equivalents of dimethylcarbonate in [D 8 ]toluene was studied. Catalytic hydrogenative depolymerization of poly(propylene carbonate).…”

A Manganese Nanosheet: New Cluster Topology and Catalysis

“…Them ild reaction conditions tolerated fluoride,t hioether, ether, amine,a nd benzyl substituents.T risubstituted alkenes were quantitatively converted at 10 bar H 2 and 60 8 8C( entries [19][20][21][22][23][24]. Them ild reaction conditions tolerated fluoride,t hioether, ether, amine,a nd benzyl substituents.T risubstituted alkenes were quantitatively converted at 10 bar H 2 and 60 8 8C( entries [19][20][21][22][23][24].…”

“…[16] Theu se of inexpensive,a bundant, and non-toxic base metals has only recently been evaluated in the context of hydrogenations. [18] In the past three years,only ahandful of homogeneous pincer-type Mn complexes were applied to hydrogenations of polar C = Xb onds,s uch as carbonyl and nitrile compounds as well as carbon dioxide,bythe groups of Beller, [19] Kempe, [20] Milstein, [21] and others. [18] In the past three years,only ahandful of homogeneous pincer-type Mn complexes were applied to hydrogenations of polar C = Xb onds,s uch as carbonyl and nitrile compounds as well as carbon dioxide,bythe groups of Beller, [19] Kempe, [20] Milstein, [21] and others.…”