Molecules 2012, 17
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carefully with wet Et2O (1 mL) and water (1 mL). The mixture was made basic with 2 M aqueous
NaOH (2 mL) and extracted with Et2O. The combined organic extracts were washed with brine, dried
over anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure. The
residue was purified by preparative TLC (hexane/Et2O = 3:1) to afford 2a (4.8 mg, 29 µmol, 29%) and
3a (7.4 mg, 45 µmol, 45%).
3,4-Dihydro-2H-thiochromen-4-ylamine (3a) [14]; 1H-NMR (CDCl3): 7.32–7.23 (m, 1H), 7.16–7.00
(m, 3H), 4.05 (brs, 1H), 3.31–3.19 (m, 1H), 2.98–2.87 (m, 1H), 2.17–2.05 (m, 2H), 1.62 (br s, 2H).
13C-NMR (CDCl3): 137.4, 132.3, 129.2, 127.4, 126.7, 124.2, 48.4, 31.0, 22.1. IR (neat, cm–1): 2920,
2849, 1583, 1566, 1472, 1435, 1286, 1074, 1042, 887, 754, 731. HRMS-EI calcd. for C9H11NS (M+)
165.0612. Found: 165.0608.
Reaction of 1a with 6.0 mol equiv. of Red-Al (Table 1, Entry 2). A two-necked 10-mL
round-bottomed flask equipped with a magnetic stirring bar was charged with 1a (18.0 mg, 100 μmol)
and dry toluene (1 mL). The solution was cooled to 0 °C. To the solution was added Red-Al (76 μL,
≥65 wt% in toluene, 600 μmol) at 0 °C, and the resulting mixture was stirred at room temperature for
0.5 h. The reaction mixture was heated at 50 °C for 6 h, cooled to 0 °C, and then treated carefully with
wet Et2O (1 mL) and water (1 mL). The mixture was made basic with 2 M aqueous NaOH (2 mL) and
extracted with Et2O. The combined organic extracts were washed with brine, dried over anhydrous
sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure. The residue was
purified by preparative TLC (hexane/Et2O = 3:1) to afford 2a (5.1 mg, 31 µmol, 31%) and 3a (2.9 mg,
18 µmol, 18%). Orlova and Kucherova reported the reaction of 1a with Red-Al, but they simply noted
the reaction in only 12 lines and no details were given [12].
Reaction of 1a with 5.9 mol equiv. of AlH3 (Table 1, Entry 4). A flame-dried 10-mL two-necked
round-bottomed flask equipped with a magnetic stirring bar was charged with LiAlH4 (16.8 mg, 443 μmol).
The LiAlH4 in the flask was stirred at 0 °C. To the stirred LiAlH4 was added dry Et2O (1.0 mL) and
AlCl3 (23.2 mg, 170 μmol). The reaction mixture was stirred at 0 °C for 1 h. To the suspension was
added 1a (18.2 mg, 100 μmol). After stirring for 0.5 h at 0 °C, the reaction mixture was warmed to
room temperature, stirred for another 2 h, cooled to 0 °C, and then treated carefully with wet Et2O (1 mL)
and water (1 mL). The mixture was made basic with 2 M aqueous NaOH (2 mL) and extracted with
Et2O. The combined organic extracts were washed with brine, dried over anhydrous sodium sulfate,
and filtered. The filtrate was concentrated under reduced pressure. The residue was purified by
preparative TLC (hexane/Et2O = 3:1) to afford 2a (7.6 mg, 46 µmol, 46%) and 3a (7.8 mg, 47 µmol, 47%).
3.2.2. Synthesis of 5,6,7,8-tetrahydro-4H-thieno[3,2-b]azepine (2d)
Reaction of 1d with 6.0 mol equiv. of AlHCl2 in CPME (Table 2, Entry 4). To a flame-dried 100-mL
two-necked round-bottomed flask equipped with a magnetic stirring bar were successively added
LiAlH4 (65.1 mg, 1.72 mmol), anhydrous CPME (10 mL), and AlCl3 (682 mg, 5.11 mmol) at 0 °C.
Stirring was continued at 0 °C for 1 h. 6,7-Dihydro-4-benzo[b]thiophenone oxime (1d, 167 mg,
1.00 mmol) was added in a small portion. After stirring for 0.5 h at 0 °C, the reaction mixture was
warmed to room temperature, stirred for another 2.5 h, cooled to 0 °C, and then treated carefully with
wet Et2O (10 mL) and 2 M aqueous NaOH (20 mL). The mixture was extracted with Et2O and the