Catalytic Asymmetric Reductive Condensation of N–H Imines: Synthesis of C₂‐Symmetric Secondary Amines

Abstract

A highly diastereoselective and enantioselective Brønsted acid catalyzed reductive condensation of N-H imines was developed. This reaction is catalyzed by a chiral disulfonimide (DSI), uses Hantzsch esters as a hydrogen source, and delivers useful C -symmetric secondary amines.

One‐Pot Synthesis of Symmetrical Tertiary and Secondary Amines from Carbonyl Compounds, Ammonium Carbonate and Carbon Monoxide as a Reductant

“…This assignment was made on the basis of the previous work. [20] Scheme 3. Scope of ortho-substituted tertiary amines in the reaction.…”

Chiral Brønsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH–Imine Hydrochloride Salts

“…Consequently, we observed the enantioselective formation of C 2 -symmetric secondary amine products, instead of the desired primary amines. 10 We speculated that if N-H imine hydrochloride salts would be used instead of the free imines, the corresponding ammonium salt products should not engage in the transimination, thereby potentially preventing the reductive dimerization. However, while anion-binding catalysis has shown utility in addition reactions to iminium salt equivalents, 11 the introduction of a stoichiometric, achiral anion (i.e., Cl -) renders such a reaction design highly challenging, as the underlying principle of asymmetric-counteranion-directed catalysis (ACDC) 12 is undermined.…”

Iron‐Catalyzed Reductive Amination from Levulinic and Formic Acid Aqueous Solutions: An Approach for the Selective Production of Pyrrolidones in Biorefinery Facilities

“…These molecules have a wide range of applications as green solvents, [21] monomers for polymer production (extensively employed in polyvinylpyrrolidone (PVP) synthesis), in nanoparticles synthesis [22][23][24] and in pharmaceutical applications. [25,26] Pyrrolidones can be synthetized by several methods, being reductive amination [27][28][29][30][31][32][33] of keto esters with concomitant lactamization, one of the best way to prepare them. Despite the many examples presented in the literature for conversion of LA into PYR, [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] some of them very efficient, the great majority uses organic solvents as reaction medium, precious metals as catalysts and do not contemplate efforts to scalingup processes.…”