page_title: Total synthesis
section_title: History
hierarchical_section_title: Total synthesis / History
context_page_description: Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes it from semisynthesis. The target molecules can be natural products, medicinally-important active ingredients, or organic compounds of theoretical interest.
  Often, the aim is to discover new route of synthesis for a target molecule for which there already exist known routes. Sometimes, however, no route exists and the chemist wishes to find a viable route for the first time. One important purpose of total synthesis is the discovery of new chemical reactions and new chemical reagents.
context_section_description: Friedrich Wöhler discovered that an organic substance, urea, could be produced from inorganic starting materials in 1828. That was an important conceptual milestone in chemistry by being the first example of a synthesis of a substance that had been known only as a byproduct of living processes. Wöhler obtained urea by treating silver cyanate with ammonium chloride, a simple, one-step synthesis:
  AgNCO + NH₄Cl → (NH₂)₂CO + AgCl
  Camphor was a scarce and expensive natural product with a worldwide demand. Haller and Blanc synthesized it from camphor acid; however, the precursor, camphoric acid, had an unknown structure. When Finnish chemist Gustav Komppa synthesized camphoric acid from diethyl oxalate and 3,3-dimethylpentanoic acid in 1904, the structure of the precursors allowed contemporary chemists to infer the complicated ring structure of camphor. Shortly thereafter, William Perkin published another synthesis of camphor. The work on the total chemical synthesis of camphor allowed Komppa to begin industrial production of the compound, in Tainionkoski, Finland, in 1907.
  The American chemist Robert Burns Woodward was a pre-eminent figure in developing total syntheses of complex organic molecules, some of his targets being cholesterol, cortisone, strychnine, lysergic acid, reserpine, chlorophyll, colchicine, vitamin B₁₂, and prostaglandin F-2a.
  Vincent du Vigneaud was awarded the 1955 Nobel Prize in Chemistry for the total synthesis of the natural polypeptide oxytocin and vasopressin, which reported in 1954 with the citation "for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone."
  Another gifted chemist is Elias James Corey, who won the Nobel Prize in Chemistry in 1990 for lifetime achievement in total synthesis and for the development of retrosynthetic analysis.
caption: Vitamin B12 total synthesis: Retrosynthetic analysis. Analysis of the Woodward–Eschenmoser total synthesis that was reported in two variants by these groups in 1972. The work involved more than 100 PhD trainees and postdoctoral fellows from 19 different nations. The retrosynthesis presents the disassembly of the target vitamin in a manner that makes chemical sense for its eventual forward construction. The target, Vitamin B12 (I), is envisioned being prepared by the simple addition of its tail, which had earlier been shown to be feasible. The needed precursor, cobyric acid (II), then becomes the target and constitutes the "corrin core" of the vitamin, and its preparation was envisaged to be possible via two pieces, a "western" part copses of the A and D rings (III) and an "eastern" part composed of the B and C rings (IV). The restrosynthetic analysis then envisions the starting materials required to make these two complex parts, the yet complex molecules V–VIII.