Cyclisation of 27 took place by alkylation (LiN(TMS), dioxane, microwave irradiation) to tricycle 28. Subsequent steps were cyanohydrin hydrolysis (camphorsulfonic acid), TMS deprotection (KOH) and allylic oxidation (SeO, tBuOH, salicylic acid) to ketone 29, then Upjohn dihydroxylation to triol 30, then acylation (AcCl, DMAP) and mesitylation (MsCl, DMAP) to 31, then benzyl group and benzyloxy group removal (hydrogenation / Palladium on carbon) followed by carbonate protection (triphosgene, pyridine) to 32, then secondary alcohol protection (TESCl, pyridine) and primary alcohol deprotection (potassium carbonate) to diol 33, then oxetane formation (DIPEA, HMPA) to 34, then acylation (AcO, DMAP), then benzoylation (phenyllithium) to 35, then oxidation (tBuOK, (PhSeO)O, THF) to the acyloin 36, then isomerisation (tBuOK) and acylation (AcO, DMAP, pyr) to 37, then oxidation at the allylic position (PCC, celite, NaOAc, benzene), ketone group oxidation (NaBH) and TES protecting group removal (HF·pyr) to baccatin III (38).