Transition metal-free catalytic reduction of primary amides using an abnormal NHC based potassium complex: integrating nucleophilicity with Lewis acidic activation

Abstract

An abnormal N-heterocyclic carbene (aNHC) based potassium complex was used as a transition metal-free catalyst for reduction of primary amides to corresponding primary amines under ambient conditions.

An NHC‐Stabilised Phosphinidene for Catalytic Formylation: A DFT‐Guided Approach

“…Simultaneously in presence of 1 , phenylsilane undergoes dehydrogenation reaction with amide to form N‐silylated amide ( 4 ) on liberation of H 2 molecule which was identified by 1 H NMR spectroscopic analysis ( δ 4.58 ppm in CD 3 CN) [58] as well as GC‐MS analysis (Figure S50) in a control reaction. Similar activation of primary amides upon liberation of hydrogen molecule by 9‐BBN through N‐borylation of primary amide has been reported in recent literature [59] . Upon the formation of the N‐silylated amide, it reacts with the phenylsilyl formate.…”

Manganese‐Catalyzed Hydroborations with Broad Scope

“…Thereduction of carboxamides typically requires harsher conditions due to the higher resonance stabilization. Chemoselectivity issues may arise from the reaction mechanism that may lead to aldehyde or amine products.T he catalytic deoxygenative hydroboration of amides to amines is as afe alternative to hydrogenations or the use of LiAlH 4 .R are earth metal catalysts were recently reported; [7f,g, 17] an abnormal N-heterocyclic carbene-potassium catalyst was active at 40 8 8C; [20] the combination KO t Bu/BEt 3 enabled amide reductions at 25-60 8 8C with pinacolborane; [21] 2,6-di-tert-butyl-phenolate lithium-THF was catalytically active at 60 8 8C. [22] Thes imple precatalyst Mn(hmds) 2 proved active in the hydroboration of alkyl and aryl carboxamides with pinacolborane to primary amines in very good yields at 50 8 8C( Scheme 3, center).…”

Manganese‐Catalyzed Hydroborations with Broad Scope

“…The catalytic deoxygenative hydroboration of amides to amines is a safe alternative to hydrogenations or the use of LiAlH 4 . Rare earth metal catalysts were recently reported; [7f,g, 17] an abnormal N ‐heterocyclic carbene‐potassium catalyst was active at 40 °C; [20] the combination KO t Bu/BEt 3 enabled amide reductions at 25–60 °C with pinacolborane; [21] 2,6‐di‐ tert ‐butyl‐phenolate lithium‐THF was catalytically active at 60 °C [22] . The simple pre‐catalyst Mn(hmds) 2 proved active in the hydroboration of alkyl and aryl carboxamides with pinacolborane to primary amines in very good yields at 50 °C (Scheme 3, center).…”