Compound 3b
2-(tert-Butoxy)propanenitrile
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InChIKey WJTSXNYRQZOSQD-UHFFFAOYSA-N
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
To a 250-mL Parr shaker bottle with a Teflon screw cap and O-ring was added 105 g (1.87 mol, 22 equiv) of liquefied isobutylene (condensed at -78 °C using a two-neck 500-mL flask and a dry-ice condenser) and 20 mL of CH2Cl2. The mixture was cooled to 0 °C (ice bath) and 5.88 g (82.7 mmol) of acetaldehyde cyanohydrin as a solution in 20.6 mL CH2Cl2 (4.0 M) was added via cannula. The shaker bottle was capped and inverted several times to achieve a clear, colorless homogenous solution and then was cooled to -78 °C (dry ice/acetone bath) and 2 mL (30.3 mmol, 0.4 equiv) of methanesulfonic acid was slowly added over 2 min via syringe. The shaker bottle was then tightly sealed with the screw cap, connected to a Parr shaker and shook for 60 h at 23 °C. The resulting clear, yellow solution was removed from the Parr shaker, re-cooled to -78 °C, and the pressure was carefully released in a well-ventilated hood. The cold reaction mixture was quenched by transferring it to a 1-L beaker containing a pre-cooled (0 °C, ice bath), stirred solution of 150 mL satd aq. NaHCO3 (aq). The shaker bottle was rinsed with diethyl ether (2 x 50 mL) and the washes were added to the beaker. The quenched mixture was stirred for 1 h at 0 °C and then was warmed to ambient temperature and stirred for an additional 3 h. The resultant biphasic mixture was poured into a 1-L separatory funnel and the organic layer was isolated. The aqueous layer was extracted with diethyl ether (2 x 100 mL) and then the organic extracts were combined, washed with brine (3 x 75 mL), and dried over MgSO4 (ca 7.5 g). The solution was filtered and the volatiles were removed by distillation at ambient pressure (bp 35-40 °C) to give 9.5 g of a clear yellow liquid. The crude mixture was purified by vacuum distillation over dried K2CO3 (0.75 g) to afford 5.2 g (50%) of 3b as a clear, colorless liquid. bp: 50–52 °C (43 mm Hg); 1H NMR: (500 MHz, CDCl3) 4.29 (q, J=6.8 Hz, 1 H, HC(2)), 1.47 (d, J=6.8 Hz, 3 H, H3C(3)), 1.25 (s, 9 H, H3C(5)); 13C NMR: (125 MHz, CDCl3) 121.36 (C(1)), 76.28 (C(4)), 56.43 (C(2)), 27.42 (C(5)), 21.73 (C(3)); IR: (KBr Pellet) 2980 (s), 2940 (m), 2876 (w), 1474 (m), 1445 (m), 1394 (m), 1370 (s), 1337 (m), 1304 (w), 1260 (m), 1239 (m), 1192 (s), 1118 (s), 1103 (s), 1063 (s), 1026 (w), 967 (s), 921 (w), 849 (m), 810 (w), 745 (w); MS: (EI, 70 meV) 127.1 (2.1), 112.1 (41.5, M+ – CH3), 102.1 (7.9), 59.1 (100.0), 57.1 (87.1), 54.1 (9.2); Analysis: C8H15NO (141.211) Calcd: C, 66.10; H, 10.30; N, 11.01% Found: C, 65.86; H, 10.25; N, 10.96%.
