Redox economy

03 April 2009 - concepts

What: Redox economy, as recently reviewed/redefined by Burns, Baran & Hoffmann (DOI) as the reduction of the number of nonstrategic (those that do not set stereochemistry or are not skeleton-building) or corrective oxidation and reduction steps in synthesis. Redox reactions impose restrictions on functional groups, they lower the overall efficiency, are difficult to scale up and generate lots of byproduct . Isohypsic reactions are multistep synthesis sequences devoid of any changes in oxidation state (rare). A synthesis does not have to be isohypsic as long as the oxidation state gradually increases or decreases as the multistep synthesis progresses. A late-oxidation state change reduces the need for protective groups. Nature is doing a great job when it comes to redox economy which Burns, Baran & Hoffmann illustrate with Taxol biosynthesis taking place by 8 oxidation steps starting from taxadiene. Recently, Andraos ranked Oseltamivir synthesis on the hypsicity scale (see previous post here)
Related to : atom economy, green metrics
Invented by: James B. Hendrickson in 1971 DOI
Related terms: Redox neutral reactions for example the Tishchenko reaction or hydrogen borrowing.