Naphthalene → tert-Butyl (2-aminocyclopentyl)carbamate

Participants

Reaction Steps

A mixture of lithium granules (1.52 g, 226.6 mmol) and naphthalene (10.9 g, 85.0 mmol) in dry dimethoxyethane (350 mL) were stirred at room temperature for 2 h. The deep blue solution was then cooled to 0° C., a solution of 4 (10.0 g, 28.33 mmol) in dry dimethoxyethane (40 mL) was added dropwise over 20 min. The mixture was stirred at 0° C. for 5 h. The undissolved lithium was filtered off, and 1 N HCl solution (60 mL) was added to the filtrate. The organic layer was separated and extracted with 1 N HCl (50 mL×2). The aqueous layers were combined, extracted with diethyl ether (50 mL×3), and then basified with 2 N NaOH solution to pH 12-14. The aqueous solution was extracted with ethyl acetate (50 mL×5). Organic layers were combined, dried over Na2SO4, solvent was removed under vacuum to afford rac-1 as a colorless oil, which solidified under vacuum to a white solid (4.08 g, 72%). Rf=0.31 (hexanes/EtOAc 2:1). Mp 60-62° C. IR (film) 3301, 2967, 1689, 1526, 1453, 1390, 1365, 1250, 1170, 1045, 1020, 870, 781 cm−1. 1H NMR (300 MHz, CDCl3) δ 4.48 (s, hr, 1H), 3.48 (m, 1H), 2.99 (m, 1H), 2.14 (m, 1H), 1.98 (m, 1H), 1.70 (m, 2H), 1.45 (s, 9H), 1.38 (m, 2H). 13C NMR (75 MHz, CDCl3) δ 156.1, 78.9, 60.5, 59.4, 33.0, 30.9, 28.4, 20.7. HRMS (EI) m/z calcd for C10H21N2O2 [M+1]+ 201.1603, found 201.1632.

Provenance & Evidence