Magnesium-catalyzed hydroboration of organic carbonates, carbon dioxide and esters

Abstract

A magnesium(i) complex was employed as a highly efficient precatalyst for the hydroboration of carbonates and esters under mild conditions.

Manganese‐Catalyzed Hydroborations with Broad Scope

“…( S )‐(+)‐2‐Methyl butyronitrile was reduced at 50 °C to the β‐chiral butylamine in near‐quantitative yield ( =6.2°, CH 3 OH). [12b] Catalytic hydroborations of carboxylates have recently been reported with transition metal catalysts, [13] bulky organo‐magnesium,[ 14 , 15 ] amidomagnesium,[ 7a , 16 ] and rare earth metal catalysts. [ 7d , 7e , 17 , 18 ] Catalytic Mn(hmds) 2 enabled clean ester reduction with HBpin at room temperature (Scheme 3 , center).…”

“…Rueping et al. reported the dibutyl‐magnesium‐catalyzed hydroboration of carbonates at 65 °C in toluene; [30] a Mg I ketiminate complex catalyzed the hydro‐boration of carbonates at room temperature; [16] lanthanum amide catalysts were recently employed by Xue et al. [7d] Following our initial observation of the efficient di‐ n ‐butyl carbonate reduction to methanol and the n ‐butyl borate (Table 1 ), we further explored the scope of this transformation in the presence of 5 mol % Mn(hmds) 2 at room temperature.…”

Recent developments in the reduction of unsaturated bonds by magnesium precursors

“…Ma and coworkers also advanced their research with magnesium metal catalysts and established highly efficient low‐valent Mg(I) metal complex for catalytic hydroboration of several organic carbonates, esters, and CO 2 . [ 64 ] 1 mol% of β –diketiminato supported Mg(I) complex 15 having Mg‐Mg bond alike with the metal complexes 11 – 13 proved as effective for the reduction of carbonates and esters with HBpin under the neat condition at room temperature (Scheme 13). The research group also applied simple, low‐cost, and readily accessible Grignard reagent for the reduction of carbonyl compounds efficiently.…”

“…A previous discussion described that Ma and coworkers established Mg(I) metal complex 15 for the reduction of CO 2 along with several organic carbonates and esters. [ 64 ] Nonetheless, an elevated temperature of 100°C for 15 h with 5 mol% of 15 was necessary for the hydroboration of carbon dioxide as displayed in Scheme 17.…”

Manganese‐Catalyzed Hydroborations with Broad Scope

“…( S )‐(+)‐2‐Methyl butyronitrile was reduced at 50 °C to the β‐chiral butylamine in near‐quantitative yield ( =6.2°, CH 3 OH) [12b] . Catalytic hydroborations of carboxylates have recently been reported with transition metal catalysts, [13] bulky organo‐magnesium, [14, 15] amidomagnesium, [7a, 16] and rare earth metal catalysts [7d–e, 17, 18] . Catalytic Mn(hmds) 2 enabled clean ester reduction with HBpin at room temperature (Scheme 3, center).…”