Beilstein J. Org. Chem. 2013, 9, 633–640.
[α]D25 −150.24 (c 0.286 g/100 mL, CHCl3); ESIMS m/z (%): 1H NMR (300 MHz, CDCl3): δ 7.51 (d, 2H), 7.41 (d, 2H), 7.02
calcd for C10H17NO3, 119.2; found, 119.0
(t, 2H), 6.59 (t, 1H), 6.38 (d, 2H), 4.46 (q, 1H), 3.97 (br s, 1H),
1.46 (d, 3H); HPLC: Chiralcel OD; n-Hex/iPrOH 99:1; 0.8 mL/
Catalyst 6. This product was purified by flash column chroma- min; tR (S) = 29.3 min, tR (R) = 35.7 min.
tography on silica gel with a 95:5 DCM/MeOH mixture as
eluent. Yield quantitative. 1H NMR (200 MHz, CDCl3) δ 7.32 4-Methoxy-N-(1-phenylethyl)aniline. This product was puri-
(m, 5H), 4.65 (dd, 1H), 3.53 (m, 2H), 2.00 (m, 4H); 13C NMR fied with a 98:2 hexane/ethyl acetate mixture as eluent. 1H
(75 MHz, CDCl3) δ 174.97 (1C), 170.71(1C), 135.5 (1C), NMR (300 MHz, CDCl3) δ 7.43–7.26 (m, 5H), 6.73 (d, 2H),
130.47 (1C), 128.27 (2C), 127.21 (2C), 59.70 (1C), 50.25 (1C), 6.58 (d, 2H), 4.46 (q, 1H), 3.74 (s, 3H), 1.58 (d, 3H); HPLC:
28.93 (1C), 25.16 (1C).
Chiralcel IB; n-Hex/iPrOH 99:1; 0.8 mL/min; tR (S) = 22.1 min,
tR (R) = 25.0 min.
Imine reduction
General procedure: As described in [8]: to a stirred solution of N-Benzyl-1-phenylethanamine. This product was purified
catalyst (0.1–0.3 mol %) in the chosen solvent (2 mL), the with an 8:2 hexane/ethyl acetate mixture as eluent. 1H NMR
imine (1 mmol) was added. The mixture was then cooled to the (300 MHz, CDCl3) δ 7.38–7.24 (m, 10H), 3.82 (q, 1H), 3.67,
chosen temperature and trichlorosilane (3.5 mmol) was added 3.60 (AB, 2H), 1.57 (bs, 1H), 1.37 (d, 3H); HPLC: Chiralcel IB;
dropwise by means of a syringe. After stirring at the appro- n-Hex/iPrOH 99:1; 0.8 mL/min; tR (R) = 8.8 min, tR (S) = 9.4
priate temperature, the reaction was quenched by the addition of min.
a saturated aqueous solution of NaHCO3 (1 mL). The mixture
was allowed to warm up to room temperature, and water (2 mL)
Supporting Information
and dichloromethane (5 mL) were added. The organic phase
was separated and the combined organic phases were dried over
Supporting Information File 1
Na2SO4, filtered, and concentrated under vacuum at room
temperature to afford the crude product. The amine was puri-
fied by flash chromatography and the absolute configuration
was determined by comparison with literature data.
Synthesis and NMR spectra of catalysts, selected HPLC
traces of the reduction products
N-(Phenyl)-1-phenylethanamine. This product was purified by
flash column chromatography on silica gel with a 98:2 hexane/
ethyl acetate mixture as eluent. 1H NMR (300 MHz, CDCl3) δ
7.23 (m, 7H), 6.61 (m, 3H), 4.48 (q, 1H), 1.53 (d, 3H). The
enantiomeric excess was determined by HPLC on a Chiralcel
OD-H (n-Hex/iPrOH 99:1; 0.8 mL/min; tR (S) = 15.4 min; tR
(R) = 18.5 min).
Acknowledgements
Financial support by MIUR-PRIN (Rome) within the national
project "Nuovi metodi catalitici stereoselettivi e sintesi stereose-
lettiva di molecole funzionali" is gratefully acknowledged. M.
B. thanks COST action CM9505 “ORCA” Organocatalysis. We
thank Prof. Franco Cozzi for helpful discussions.
References
N-(1-Phenylpropyl)aniline. This product was purified with a
98:2 hexane/ethyl acetate mixture as eluent. 1H NMR
(300 MHz, CDCl3) δ 7.31 (m, 4H), 7.21 (m, 1H), 7.07 (t, 2H),
6.62 (t, 1H), 6.50 (d, 2H), 4.21 (t, 1H), 4.05 (br s, 1H), 1.81 (m,
2H), 0.94 (t, 3H); HPLC: Chiralcel IB; n-Hex/iPrOH 99:1; 0.8
mL/min; tR (S) = 7.9 min, tR (R) = 8.5 min.
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2H), 6.7 (m, 3H), 4.6 (q, 1H), 3.97 (br s, 1H), 1.6 (d, 3H);
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