Reaction Steps
Following the procedure described for the synthesis of 13a, compound 13b was recovered from 12b as a yellow oil (88% yield). [α]D+8.7 (c 1.4, CHCl3). 1H-NMR (400 MHz, CDCl3): δ 0.87 (3H, s, pinanyl CH3), 1.11 (1H, d, J 11.0, pinanyl Hendo), 1.32 (3H, s, pinanyl CH3), 1.43 (3H, s, pinanyl CH3), 1.63 (9H, s, t-Bu), 1.84-2.39 (5H, m, pinanyl protons), 2.42 (2H, s, BCH2), 4.32 (1H, dd, J 8.8, 2.0, CHOB), 7.33 (1H, t, J 7.7, H5), 7.40 (1H, d, J 7.7, H6), 7.80 (1H, d, J 7.7, H4), 7.86 (1H, s, H2). 13C-NMR (100 MHz, CDCl3): δ 19.3 (CB), 24.0, 26.5, 27.1, 28.2, 28.6, 35.4, 38.2, 39.5, 51.3, 78.0, 80.7, 86.0, 126.2, 128.1, 129.9, 132.0, 133.2, 139.0, 166.0; EI-MS: m/z 370 (M+, 18%), 314 (71), 297 (59), 135 (55), 57 (100). Anal. Calcd. for C22H31BO4: C, 71.36; H, 8.44. Found: C, 71.60; H, 8.27.
