The combination of asymmetric hydrogenation of olefins and direct reductive amination

Abstract

Asymmetric hydrogenation (AH) and direct reductive amination (DRA) are both efficient transformations frequently utilized in industry. Here we combine the asymmetric hydrogenation of prochiral olefins and direct reductive amination of aldehydes in one step using hydrogen gas as the common reductant and a rhodium-Segphos complex as the catalyst. With this strategy, the efficiency for the synthesis of the corresponding chiral amino compounds is significantly improved. The practical application of this synthetic approach is demonstrated by the facile synthesis of chiral 3-phenyltetrahydroquinoline and 3benzylindoline compounds.

Construction of α-Alkylated Amines by Iridium Complex-Catalyzed One-Step Transfer Hydrogenation of C=C and C=N Bonds

“…12 Chang's group presented an Ru-Segphos complex-catalyzed asymmetric hydrogenation of prochiral olefins and imines. 13 It needs to be pointed out that Xiao's group reported one example of one-pot transfer hydrogenation of C=C bond and reductive amination of C=N bond, using iridium complex as catalyst, and formic acid and formate as hydrogen sources. 14 Among these reported methods, transfer hydrogenation has outstanding merits: (i) the hydrogen donors are readily available, inexpensive, and easy to handle and (ii) the catalysts are readily accessible and compatible, and the process is operationally simple.…”

“…1 H and 13 C NMR spectra were recorded on a Bruker DRX-400 spectrometer (400 MHz for 1 H; 100 MHz for 13 C) using CDCl3 as solvent and TMS as an internal standard. The chemical shifts are referenced to signals at 7.26 and 77.0 ppm, respectively.…”

“…1 H NMR (400 MHz, CDCl 3 ):  = 7.36 (t, J = 7.4 Hz, 2 H), 7.27 (dd, J = 11.5, 7.2 Hz, 3 H), 6.98-6.87 (m, 2 H), 6.56-6.48 (m, 2 H), 3.46 (dt, J = 12.6, 6.3 Hz, 1 H), 2.78 (q, J = 7.3 Hz, 2 H), 1.99-1.77 (m, 2 H), 1.27 (d, J = 6.3 Hz, 3 H). 13…”

“…1 H NMR (400 MHz, CDCl 3 ):  = 7.35 (t, J = 7.3 Hz, 2 H), 7.26 (dd, J = 13.5, 7.1 Hz, 3 H), 7.06 (d, J = 8.3 Hz, 2 H), 6.54-6.48 (m, 2 H), 3.49 (dd, J = 12.7, 6.3 Hz, 2 H), 2.78 (t, J = 7.7 Hz, 2 H), 1.96-1.80 (m, 2 H), 1.27 (d, J = 6.3 Hz, 3 H). 13 C NMR (100 MHz, CDCl 3 ):  = 146. 3,141.7,139.9,128.4,128.4,125.9,122.4,121.3 (q,J = 254 Hz),113.1,48.0,38.6,32.4,20.6.…”

“…1 H NMR (400 MHz, CDCl 3 ):  = 7.42-7.37 (m, 2 H), 7.35-7.29 (m, 2 H), 7.27-7.17 (m, 3 H), 6.50-6.44 (m, 2 H), 4.10 (d, J = 6.8 Hz, 1 H), 3.61-3.45 (m, 1 H), 2.74 (dd, J = 11.4, 4.7 Hz, 2 H), 1.96-1.80 (m, 2 H), 1.27 (d, J = 6.4 Hz, 3 H). 13 C NMR (100 MHz, CDCl 3 ):  = 150. 7, 141.4, 133.8, 128.54, 128.4, 126.1, 120.7, 112.4, 98.1, 47.50, 38.4, 32.3, 20.6.…”