1. Use of 15N-HMBC NMR techniques to determine the orientation of the steroidal units in ritterazine A1
2. 15N chemical shifts and long-range1H-15N coupling pathways of selectedstrychnosalkaloids
3. Gradient selection in inverse heteronuclear correlation spectroscopy
4. Physico-chemical properties of YM-75518 (1); Appearance; white powder, m.p. 126–128°C, [α]D25=−13.9 (c 3.70, in MeOH), IR (KBr) 3440, 2920, 1750, 1730, 1650, 1530, 1450, 1390, 1260 cm−1, UV (EtOH) λmax 282 (ε 9000) 211 (ε 11000), 13C NMR (125MHz, CD3OD) δ 148.7 (C1), 135.6 (C2), 126.2 (C3), 164.3 (C4), 126.9 (C5), 109.9 (C6), 35.7 (C7), 73.1 (C8), 39.0 (C9), 171.9 (C10), 73.8 (C11), 20.2 (C12), 132.7 (C13), 135.1 (C14), 73.4 (C15), 139.4 (C16). 19.7 (C17), 125.7 (C18), 33.2 (C19), 141.4 (C20), 121.0 (C21), 132.0 (C22), 114.5 (C23), 156.8 (C24), 122.2 (C25) and 170.1 (C26)