(–)-Quinine

I recall a conversation with my industrial supervisor during my first week as a process chemist while he was explaining the background to my project. ‘Really? You made 100kg using this route? It’s fifteen steps long!’ I said, looking at the number of arrows in the scheme. ‘Well,’ he replied patiently, ‘we actually only isolated one intermediate, so in a sense it’s only two steps long’.

In this age of telescoping, scalable total synthesis and fierce competition, the definition of a chemical step – and therefore who has the shortest route to a target – can be controversial. New technologies such as biocatalytic cascades and flow chemistry make it easier than ever to avoid isolating intermediates, and chemists seem to squeeze more and more information over their arrows with every passing decade.