3.5.1. (*S*)-MTPA Ester of **7** (**7**-4*S*)

White amorphous solid; 1H NMR (CD3OD, 800 MHz) δ<sup>H</sup> 7.574–7.566 (2H, m, MTPA-Ar), 7.457–7.435 (3H, m, MTPA-Ar), 5.864 (1H, dd, *J* = 6.5, 5.0 Hz, H-4), 5.227 (1H, dq, *J* = 8.7, 1.1 Hz, H-12), 4.789 (1H, td, *J* = 9.1, 3.8 Hz, H-11), 3.903 (1H, dd, *J* = 4.6, 1.5 Hz, H-8), 3.633 (3H, s, H-22), 3.574 (3H, s, MTPA-OMe), 2.591 (1H, d, *J* = 18.2 Hz, H-7α), 2.512 (1H, dd, *J* = 8.2, 5.2 Hz, H-2α), 2.488 (1H, m, H-2β), 2.474 (1H, m, H-3α), 2.371 (1H, m, H-17), 2.346 (1H, m, H-10α), 2.238 (1H, m, H-3β), 2.192 (1H, ddd, *J* = 18.1, 4.5, 1.0 Hz, H-7β), 2.022 (2H, m, H-14), 1.945 (1H, dd, *J* = 13.7, 3.7 Hz, H-10β), 1.654 (3H, d, *J* = 1.1 Hz, H-20), 1.612 (1H, m, H-16α), 1.428 (2H, m, H-15), 1.411 (1H, m, H-16β), 1.122 (3H, d, *J* = 7.0 Hz, H-21), 1.015 (3H, s, H-19); LRESIMS *m*/*z* 609.2 [M + H]+.
