Reaction Steps
A solution of hydrazine (6.59 g, 6.40 mL, 205.5 mmol) in MeOH (110 mL) was added dropwise to a solution of the nitro-compound 24 (18.1 g, 41.1 mmol), over anti-bumping granules and Raney Ni (2.6 g) in MeOH (325 mL) and heated at reflux. After 1 hour at reflux TLC (95% CHCl3/MeOH) revealed some amine formation. The reaction mixture was treated with further Raney Ni (2.6 g) and hydrazine (6.40 mL) in MeOH (50 mL) and was heated at reflux for an additional 30 minutes at which point TLC revealed reaction completion. The reaction mixture was then treated with sufficient Raney Ni to decompose any remaining hydrazine and heated at reflux for a further 1.5 h. Following cooling to room temperature the mixture was filtered through a sinter and the resulting filtrate evaporated in vacuo. The resulting residue was then treated with CH2Cl2 (300 mL), dried (MgSO4), filtered and evaporated in vacuo to provide the amine 25 as a green oil (16.03 g, 95%): [α]22D=−116.32° (c=0.31, CHCl3); 1H NMR (270 MHz, CDCl3) (Rotamers) δ 6.70 (s, 1H), 6.28 (s, 1H), 4.51-4.49 (m, 1H), 4.36-4.34 (m, 1H), 4.06-3.77 (m, 10H), 3.61-3.50 (m, 3H), 2.23-2.21 (m, 1H), 2.01-1.98 (m, 1H), 0.89 (s, 9H), 0.04 (s, 6H); 13C NMR (67.8 MHz, CDCl3) (Rotamers) δ 170.2, 151.5, 141.2, 140.5, 112.2, 112.0, 101.1, 70.4, 62.6, 59.0, 56.9, 56.6, 55.8, 35.7, 25.9 and 25.7, 18.2, −5.4 and −5.5; MS (EI), m/z (relative intensity) 412 (M++2, 3), 411 (M++1, 10), 410 (M+, 32), 354 (6), 353 (23), 263 (3), 212 (5), 181 (11), 180 (100), 179 (3), 165 (3), 164 (6), 152 (10), 137 (4), 136 (4), 125 (5), 120 (3), 100 (3), 94 (6), 75 (9), 73 (7), 57 (3); IR (CHCl3) 3353 (br), 2953, 2930, 2857, 1623, 1594, 1558, 1517, 1464, 1435, 1404, 1260, 1234, 1215, 1175, 1119, 1060, 1005, 915, 836, 777, 755, 666 cm−1; exact mass calcd for C20H34N2O5Si m/e 410.2237, obsd m/e 410.2281.
