Semisynthesis is usually used when the precursor molecule is too structurally complex, too costly or too inefficient to be produced by total synthesis. It is also possible that the semisynthetic derivative outperforms the original biomolecule itself with respect to potency, stability or safety.
Drugs derived from natural sources are usually produced by harvesting the natural source or through semisynthetic methods: one example is the semisynthesis of LSD from ergotamine, which is isolated from ergot fungus cultures. The commercial production of paclitaxel is also based on semisynthesis (see: paclitaxel total synthesis).
The antimalarial drug artemether (a component of Coartem) is a semisynthetic derived from naturally occurring artemisinin. The latter is unstable due to the presence of a lactone group and therefore this group is replaced by an acetal through organic reduction with potassium borohydride and methoxylation :
Microwave- and ultrasound-assisted semisynthesis of natural methoxylated propiophenones from isomeric mixture of phenylpropenes in minutes (1).
Oct 01, 2005; Introduction Methoxylated propiophenones (1) are isolated from a large number of medicinally important plants and possess a wide...
US Patent Issued to Indena on Nov. 27 for "Semisynthesis Process for the Preparation of 10 Deacetyl-N-Debenzoyl-Paclitaxel" (Italian Inventors)
Nov 29, 2012; ALEXANDRIA, Va., Nov. 29 -- United States Patent no. 8,318,957, issued on Nov. 27, was assigned to Indena S.p. A. (Milan)....