7-O-(Triethylsilyl)-2'-O-tert-butyl(dimethyl)silyl-isocephalomannine is an intermediate used in the synthesis of Iso Cephalomannine (I789500), which is a Cephalomannine (C258500) isomer as an impurity in Paclitaxel (P132500) active pharmaceutical ingredient. Paclitaxel impurity A. It binds to the N-terminal 31 amino acids of the beta-tubulin subunit in the microtubule, rather than to tubulin dimers. Paclitaxel - impurity A. Molecular Formula: C57H81NO14Si2 Molecular Weight: 1060.42