Tetrabutylammonium Fluoride → Tert-butyl(1S)-1-(2-(2-hydroxyethyl)cyclopropyl)-3-methylbutylcarbamate

Participants

Reaction Steps

To a solution of the crude TBDPS-protected alcohol 11a (464 mg, 0.742 mmol) in dry THF (6 mL) at 0° C. was added TBAF (1.0M/THF, 0.93 mL, 0.927 mmol), and the reaction mixture was allowed to warm to rt while stirring under N2. Since TLC showed uncomplete reaction after 5 h, 0.75 eq. TBAF (0.56 mL) was added. After 9 h, the reaction mixture was quenched with sat. aq. NH4Cl and diluted with EtOAc. The aqueous phase was separated and extracted with EtOAc. The combined organic layers were washed with brine, dried (Na2SO4), filtered and concentrated in vacuo. Flash chromatography (SiO2, 5:5, hexanes/EtOAc) afforded 177 mg (88%) of the title compound as a colorless oil which solidified upon high vacuum to give a white powder. mp 49.8-50.2° C.; [α]D22-30.8 (c 1.0, DCM); 1H NMR (300 MHz, CDCl3) δ 4.50 (appbd, 1 H, J=4.5 Hz), 3.66 (bs, 2 H), 2.94 (m, 1 H), 2.36 (bs, 1H), 1.82 (m, 1 H), 1.71 (m, 1 H), 1.45 (s, 9 H), 1.39 (t, 2 H, J=7.2 Hz), 1.01 (bs, 2 H), 0.90 (dd, 6 H, J=10.2, 6.6 Hz), 0.50 (m, 1 H), 0.43-0.27 (m, 2 H); HRMS (ESI) m/z calcd for C15H29NO3Na 294.2045. found 294.2064.

Provenance & Evidence