S19, S20 tert-Butyl (23) S21, S22 tert-Butyl (24) S23, S24 tert-Butyl (25) S25, S26 tert-Butyl (26) S27, S28 (Z-27) S29, S30 tert-Butyl
tert-Butyl (23) S19, S20 tert-Butyl (24) S21, S22 tert-Butyl (25) S23, S24 tert-Butyl (26) S25, S26 (Z-27) S27, S28 tert-Butyl S29, S30