Cooperative photocatalysis and l-/d-proline catalysis enables enantioselective oxidative cross-dehydrogenative coupling of acyclic benzylic secondary amines with ketones

Abstract

Herein, we developed a new enantioselective oxidative cross-dehydrogenative coupling of acyclic benzylic secondary amines with simple ketones by combining photocatalysis and L-/D-proline catalysis. A variety of acyclic benzylic secondary amines...

Direct enantioselective α-alkylation of secondary acyclic amines with ketones by combining photocatalysis and lipase catalytic promiscuity

“…The absolute configurations of all products were determined by comparison with previously reported chiral HPLC analysis. 26,30–38…”

“…Based on the performed experiments and previous literature, 25–27,45–50 a possible mechanistic pathway for the reaction was proposed as depicted in Fig. 3.…”

“…A series of chiral β-amino ketones were obtained in good yields with moderate enantio- and diastereoselectivities. Different from the previous work on asymmetric α-alkylation of secondary acyclic amines with ketones, 23–27 the protocol reported here represents the first example of a photoenzymatic approach for the direct enantioselective α-alkylation of secondary acyclic amines.…”

“…On the other hand, the direct α-alkylation of amines has emerged as one of the most straightforward and atom-economical strategies for constructing C–C bonds in N-containing compounds. Among them, asymmetric α-alkylation of secondary acyclic amines with ketones has been achieved by chemical oxidation, 23 transition metal catalysis, 24 photoredox catalysis 25,26 and electrochemistry 27 (Fig. 1d).…”

“…Currently, chiral catalysts are limited to complicated metal complexes, 23,24 chiral amines, 25,27 and proline. 26 So far, photoenzymatic catalysis has not been employed for the direct enantioselective α-alkylation of secondary acyclic amines with ketones.…”