Switching Selectivity in Copper-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amine-Boranes and Secondary Amines under Mild Conditions

Abstract

A simple and efficient copper-catalyzed selective transfer hydrogenation of nitriles to primary amine-boranes and secondary amines with an oxazaborolidine–BH3 complex is reported. The selectivity control was achieved under mild conditions by switching the solvent and the copper catalysts. More than 30 primary amine-boranes and 40 secondary amines were synthesized via this strategy in high selectivity and yields of up to 95%. The strategy was applied to the synthesis of 15N labeled in 89% yield.

Construction of biomass-based amines via Ir-mediated N-alkylation: kinetic analysis

“…Based on the above discussions, the kinetic analysis on Scheme 5a leads to the ordinary differential equations (eqn ( 8)- (12), see Scheme S3 for the kinetic equations in the ESI †). During the reaction, the Ir catalyst is 1.4 mol% relative to 2a and it is always true for eqn (13) (Scheme S3 †) with [Cat] 0 as the initially loaded catalyst amount. Moreover, both [Cat] and [Cat H 2 ] can be regarded as constants, and thus be included in the corresponding k based on the pseudo-order rate law without accounting for the changes of the catalyst-concentration and catalyst-deactivation.…”

“…To address this issue, the hydrogenative homocoupling of 2-furonitrile (11) for 5m synthesis (Scheme 1b) was examined by a variety of catalysts, such as Ir, Cu, and PdNi. [12][13][14] However, the hydrogenative homocoupling method generally suffers from a very limited substrate scope. Moreover, only symmetrical secondary amines can be obtained using this strategy.…”

Pd-Catalyzed Homologation of Arylboronic Acids as a Platform for the Diversity-Oriented Synthesis of Benzylic C–X Bonds

“…Template for SYNLETT Thieme typically require the use of stochiometric organometallic reagents from halides, 1,22 hydroboration, 1,23 C-H activation, 24 or photoredox 25 methods. As a conceptual alternative to the classical Matteson homologation, 26 which inserts a metalated carbenoid into an organoboron reagent, 27 we have recently disclosed an approach using Pd catalysis, arylboronic acids and a halomethylboronic acid pinacol ester.…”

“…The spectral data were consistent with the literature. 24 This article is protected by copyright. All rights reserved.…”

Room Temperature Reduction of Titanium Tetrachloride-Activated Nitriles to Primary Amines with Ammonia-Borane

“…Oxoborane derivatives, such as catecholborane or pinacolborane, which are slow in their reactivity compared to borane or its alkyl derivatives have also been used to reduce nitriles by using transition metal activators as catalysts [25][26][27][28] (Scheme 1v). Several metal-catalyzed transfer hydrogenations (TH) using amine-boranes, including ammonia-borane to convert a nitrile to an amine have also been reported recently (Scheme 1vi) [29][30][31][32][33][34]. Diisopropylaminoborane generated via the dehydrogenation of the corresponding amine-borane has been shown to be effective for the reduction of nitriles to amines [35] (Scheme 1vii).…”