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With 4-methyl-morpholine; isobutyl chloroformate; In tetrahydrofuran; at -78 - 20℃; for 3.0h;
Isobutyl chloroformate (0.7 mL) was added to (+/-)-Boc-amino-3-thienyl- glycine (1.505 g, 5.85 [MMOL)] and N-methylmorpholine [(O.] 7 mL) in THF (15 mL) and the reaction mixture was stirred at-78 [C] for 1 h. A mixture of 3- aminoindan (950 mg, 7.13 [MMOL)] and [N-METHYLMORPHOLINE] (0.7 mL) in THF (7 mL) was added and the resulting mixture was stirred for 2 h, slowly warming to RT. The mixture was partitioned between [DICHLOROMETHANE] (200 mL) and water (50 mL). The organic layer was washed sequentially with water (50 mL), HCI [(1M,] 50 mL), and brine (50 mL) and dried over sodium sulfate. Filtration through a small plug of silica gel followed by evaporation to remove the solvent yielded a solid, which was triturated with hexane to provide a product (1. 82 g, 84%) sufficiently pure for the next step
Example 1 Preparation of tert-butyl 2-hydroxy-1-(thiophen-3-yl)ethylcarbamate (E1) To (+-)-2-(tert-butoxycarbonylamino)-2-(thiophen-3-yl)acetic acid in THF at 0 C. was added BH3-THF dropwise. The solution was allowed to warm to room temperature and stirred for an additional 2 hours. The solution was cooled to 0 C., quenched with AcOH (10%)/MeOH and evaporated. Column chromatography (SiO2, EtOAc) gave pure tert-butyl 2-hydroxy-1-(thiophen-3-yl)ethylcarbamate (E1).
With borane-THF; In tetrahydrofuran; at 0 - 20℃; for 2.0h;
To (±)-2-(/cT/-butoYcarbonylamino)-2-(thiophen-3-yl)acetic acid in THF at 0 C was added BH3-THF dropwise. The solution was allowed to warm to room temperature and stirred for an additional 2 hours. The solution was cooled to 0 C, quenched with AcOH (lO%)/MeOH and evaporated. Column chromatography (SiCF. EtOAc) gave pure /e/V-butyl 2-hydroxy-l-(thiophen-3-yl)ethylcarbamate (El).