Transition metal-catalysis in interrupted borrowing hydrogen strategy

Abstract

In recent times, the transition metal-catalyzed borrowing hydrogen (BH) and interrupted borrowing hydrogen (IBH) strategies have attracted much attention and represent atom- and step-economic processes to access diverse building blocks...

Divergence in CH alkylation of indoles under Mn catalysis

“…Thus, Mn( ii )–NNN follows an interrupted borrowing hydrogen (IBH) strategy. 19 Notably, the in situ generated [ Mn-5 ] complex did not yield the expected product in good yield (∼53% BIM). This result demonstrates the necessity and importance of molecularly defined complexes.…”

One-pot three-component synthesis of α-methylated ketones from secondary and primary aryl alcohols

“…Alternatively, with the use of alcohol as the starting material, additional hydrogen released by dehydrogenation of secondary alcohol could further reduce the products (Scheme 1(b)) and therefore present a selectivity and purification problem. 13 Furthermore, the primary and secondary alcohols are prone to give undesired self-coupling 14 a – c as well as cross-coupling 14 d products.…”

CrCl2-catalyzed α-alkylation of carbonyl compounds via a borrowing hydrogen approach

“…1 Among these transformations, α-alkylation of carbonyl compounds proceeding via borrowing hydrogen has been widely recognized as an attractive approach for sustainable organic synthesis, since in this one-pot process, naturally abundant, cost-effective and benign alcohols have been utilized directly as alkylating agents and the sole byproduct was water. 2 Early methods for C -alkylation based on the borrowing hydrogen procedure predominately involved precious metal catalysts such as ruthenium, 3 iridium, 4 palladium, 5 osmium, 6 and rhodium. 7 In recent years, considering sustainability, attention has shifted toward economical and less-toxic catalysts based on Earth-abundant 3d metals and manganese, 8 iron, 9 cobalt, 10 nickel, 11 and copper complexes 12 have been widely employed (Scheme 1a).…”