Scope and mechanism of nitrile dihydroboration mediated by a β-diketiminate manganese hydride catalyst

Abstract

Nitrile insertion allows for manganese-catalyzed nitrile dihydroboration at 80 °C.

Catalytic Nitrile Hydroboration: A Route to N,N‐Diborylamines and Uses Thereof

“…[19,20] During the last decade, since the discovery of Mo-catalyzed dihydroboration of nitriles, [19,20] a number of research publications concerning other catalytic systems have appeared in the literature, with the vast majority of developments being accomplished in the area of transition metal catalysis. The newly developed methods mostly rely on Ru [22,29,30] and Co [21,23,31,32] catalysts, with a handful of examples using Ti, [33,34] Mn, [35] Fe [36] and Ni. [37] With regards to f-block elements, only two reports on using Er, Y, Dy, Gd [38] and Th [39] systems in dihydroboration of nitriles have been disclosed.…”

“…Moving beyond ruthenium systems, a series of abundant base metal catalysts (Fe, [36] Co, [21,23,31,32] Ni [37] and Mn [35] ) have been reported to facilitate hydroboration of nitriles. Thus, ironcatalyzed reactions were disclosed by Nakazawa et.…”

“…In 2020, Baik and Trovitch demonstrated double addition of HBPin to nitriles catalyzed by β-diketiminate (NacNac) Mn(II) hydride complex [( Dipp BDI)Mn(μ-H)] 2 (15; Scheme 17). [35] Using 0.5 mol% of 15, the reactions were conducted in benzene-d 6 at 80°C for 24 hours and showed full conversion of a series of aliphatic nitriles and benzonitriles with different electron-donating and electronwithdrawing substituents to the corresponding N,N-diborylamines, isolated in good yields (Scheme 17). Similar to the Co systems reported previously by the same group (Schemes 11 and 12), [23,31] Mn-catalyzed reduction of 4-acetylbenzonitrile proved non-selective resulting in reduction of on both keto and nitrile functional groups.…”

“…Besides nickel, one example of hydroboration of nitriles has been recently reported for manganese. In 2020, Baik and Trovitch demonstrated double addition of HBPin to nitriles catalyzed by β‐diketiminate (NacNac) Mn(II) hydride complex [( Dipp BDI)Mn(μ‐H)] 2 ( 15 ; Scheme ) . Using 0.5 mol% of 15 , the reactions were conducted in benzene‐d 6 at 80 °C for 24 hours and showed full conversion of a series of aliphatic nitriles and benzonitriles with different electron‐donating and electron‐withdrawing substituents to the corresponding N,N‐diborylamines, isolated in good yields (Scheme ).…”

Sodium as High‐efficient Catalyst in Hydroboration of Unsaturated Compounds

“…[7] The hydroboration catalyzed by well-defined transition metal catalysts is particularly prevalent. Numerous transition metal complexes involving Mo, [8] Fe, [9] Co, [10] Ru, [11] Th, [12] Hf [13] , Ti, [14] Zn, [15] and Mn [16] have exhibited outstanding catalytic activity, and a variety of valuable organoboranes are formed. Besides, the Lewis acid/Lewis acid-base pairs synthesized by main group catalysts based on Mg [17] and Al [3b,18] have achieved great success in the hydroboration of nitriles with high efficiency.…”