Synthesis of (–)‐(S)‐Norlaudanosine, (+)‐(R)‐O,O‐Dimethylcoclaurine, and (+)‐(R)‐Salsolidine by Alkylation of an α‐Aminonitrile

Abstract

A short asymmetric synthesis of 1-substituted 1,2,3,4-tetrahydroisoquinoline alkaloids by deprotonation of an unprotected α-aminonitrile and alkylation of the resulting carbanion followed by spontaneous elimination of HCN and asymmetric reduction is described.

1,3‐Benzyl Migration in Iminium Ions: Evidence for a Fast Free‐Radical Chain Reaction

“…ESI-HRMS spectra were recorded with a highresolution Q-TOF spectrometer with a dual source and a suitable external calibrant. The 1-substituted 1,2,3,4-tetrahydroisoquinolines 15a, [13] 15b [14] and 15h [13] shown in Table 1 were prepared according to known procedures.…”

“…1 H NMR (400 MHz, CDCl 3 ): δ = 6.99 (s, 1 H, 3-H), 6.86 (s, 1 H, 6-H), 4.72 (d, J = 6.3 Hz, 2 H, Ar-CH 2 ), 1.84 (t, J = 6.3 Hz, 1 H, OH) ppm. 13 C NMR (100.6 MHz, CDCl 3 ): δ = 130.5 (C-1), 123.7 (C-6), 112.6, 111.8 (C-2, C-5), 62. 7-Ethoxy-6-methoxy-1,2,3,4-tetrahydroisoquinoline-1-carbonitrile: A solution of KCN (198 mg, 1.81 mmol) in water (1.04 mL) was added to a solution of 7-ethoxy-6-methoxy-3,4-dihydroisoquinoline [19] (198 mg, 964 μmol) in MeOH (253 μL).…”

“…A solution of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-1-carbonitrile [13,15] (797 mg, 3.65 mmol) in dry THF (12 mL) was cooled to -78°C. A solution of KHMDS (1.46 g, 7.31 mmol) in dry THF (20 mL) was added slowly.…”

Applications of N′-alkylated derivatives of TsDPEN in the asymmetric transfer hydrogenation of CO and CN bonds

“…9 Absolute configurations were obtained by comparison with the reported data. [10][11][12][13][14][15] except 34 and 36, which were assigned by analogy with 22 and 32.…”

Multicomponent C‐Alkylation Reactions of Aromatic Aldimines with Trialkylboranes Reagents

“…1-Ethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (6): [14] Boron trifluoride-diethyl ether (250 µL, 2 mmol) was added to a solution of 6,7-dimethoxy-3,4-dihydroisoquinoline [15] (191 mg, 1 mmol) in dichloromethane. The reaction mixture was stirred at room temperature for 10 min and then a 1  solution of triethylborane in hexane (3 mL, 3 mmol) was added.…”