Compound 2h
(1S,2R,3S)-1-(but-3-en-1-yl)-2-hydroxy-N,N,2,3-tetramethylcyclopentane-1-carboxamide
From: Enantioselective cyclizations and cyclization cascades of samarium ketyl radicals
View in PubChem | NMR | MDL Molfile | ChemDraw
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Prepared according to general procedure 2 outlined for compound 2a from 2-acetyl-2-(but-3-en-1-yl)-N,N-dimethylhex-5-enamide 1h (31.8 mg, 0.134 mmol). After a reaction time of 72 h at −40 °C, the crude product was separated from the ligand (see Note B above) and purified by column chromatography (hexane/EtOAc 90:10) to afford diastereopure 2h as a pale yellow oil (10.9 mg, 34%, er: 50:50). 1H NMR (400 MHz, CDCl3) δ6.25–6.11 (bs, 1 H, OH), 5.85–5.69 (m, 1 H, CH=CH2), 5.00 (d, 1 H, J = 17.3 Hz, CH=CHcisHtrans), 4.93 (d, 1 H, J = 10.2 Hz, CH=CHcisHtrans), 3.18–2.90 (bs, 6 H, N(CH3)2), 2.60–2.42 (m, 1 H, CHaHbCH2CH=CH2), 2.28–2.15 (m, 2 H, CHaHbCCON(CH3)2 + CH3CH), 1.89–1.74 (m, 4 H, CH2CH2CH=CH2 + CHaHbCH2CH=CH2 + CHaHbCH2CCON(CH3)2), 1.66–1.57 (m, 1 H, CHaHbCCON(CH3)2), 1.17–1.09 (m, 1 H, CH3CHCHaHb), 1.07 (s, 3 H, CH3COH), 0.94 (d, 3 H, J = 6.9 Hz, CH3CH); 13C NMR (100 MHz, CDCl3) δ178.9 (CON(CH3)2), 138.5 (CH=CH2), 114.4 (CH=CH2), 84.7 (COH), 54.8 (CCON(CH3)2), 42.2 (CH3CH), 38.4 (b, 2C: N(CH3)2), 34.0 (CH2CH2CH=CH2) 32.5 (CH2CCON(CH3)2), 29.6 (CH2CH2CH=CH2), 28.4 (CH3CHCH2), 18.1 (CH3COH), 14.5 (CH3CH); IR νmax (neat/cm-1): 3326, 2925, 2872, 2346, 1735, 1640, 1600, 1456, 1379, 1255, 1116, 1055, 909, 800; HRMS (APCI) calcd for C14H26O2N, [M+H]+: 240.1958, found 240.1960.
The racemic nature of the product was determined by GC analysis (Chiraldex® G-TA 30 m x 0.25 mm column, 70 °C to 130 °C (0.2 °C/min)/isothermal at 130 °C, flow rate = 1.0 mL/min, retention time: 340.1 min, 343.6 min; er: 50:50.
