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Working on partial syntheses of cortisone


Steroid chemistry and synthesis
Carl Djerassi Scientist
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I really have to digress and... and go into steroid chemistry for a moment because it’s impossible to do this just by just speaking and it’s actually easier to do it here. Because if you... if you look at this... this is what a steroid molecule looks like. Steroid nowadays are a dirty word. People remember steroids... anabolic steroids, which were misused by... by athletes. In the 1940s steroid meant... if you’re on steroids that you’re on cortisone, but both of these are, of course, silly and completely meaningless descriptions because steroid is a chemical definition and not a biological one. And it simply means any compound that is based on this tetracyclic skeleton, four rings, three six-membered and one five-membered ring fused in that particular way, which is a fairly complex thing even. And you want to remember that even as it’s drawn here... well, you see it up on top. It’s all carbons and hydrogens. Carbon is the C and hydrogen is H, but then as a shorthand we don’t write this and we write it like it is shown down below it. So, a steroid is any compound that is based chemically on this. Biologically it’s an enormous number of different compounds, which as I mentioned included the male and female sex hormones, the adrenal hormones, vitamin D, the cardiac leukocytes, the toad poisons, vitamin D... you can... you can go on and on. The diuretic hormone, aldosterone, and etc, etc.

So, it’s a... an extremely important area of chemistry, but it’s a difficult one. And I’m digressing chemically... digressing chemically for a moment. That’s also important to explain the difference between total synthesis and partial synthesis. Before I just said the word synthesis, but synthesis really has to be defined. Total synthesis means you start from scratch and basically it means air, water and coal tar, benzene if you wish. And you can do... synthesise anything from that starting material, from those starting materials. Well, that is total synthesis in a very crude sense. Partial synthesis is that you start already with something that you transform into something else, and the best analogy is an architectural one. Speaking to you as a wife of an architect you would perhaps appreciate it more. So total synthesis is you start building... First of all the architectural analogy is also important because a chemist is both architect and builder whereas in most countries, though not all of them, these two professions are separated. They’re not for instance, in some of the Latin American countries where the architect is also the builder. But as chemists we pride ourselves we are both architects and builders and we refuse to be relegated just to the function of builder where the architect would have the fancy design and the builder has to do the dirty work. But you want to do both. Now... so total synthesis is building a house from scratch. You take from wood, whatever it is, stone, brick, concrete... from scratch. You have nothing and you build it up. Partial synthesis is transfer one... transform one into the other. I mean you could have a barn and you convert the barn into a real villa and, you know, you add plumbing and divisions and rooms, and etc, etc. And eventually that barn will be totally unrecognisable but it already had a foundation. It already had walls and something like that.

So that is partial synthesis. And all the steroids at that time were, with one exception, were all synthesised partially. That is by transforming one building into another. There had been only one total synthesis of, in some respects, the simplest hormone called equilenin, which is an oestrogen female sex hormone of horses. It occurs in horses’ urine. Not in human urine. So equilenin, that comes from that and that synthesis was accomplished by my former professor, Wilds, when he was a graduate student at the University of Michigan with his professor Bachman. And that synthesis, Bachman, Cole and Wilds [alphabetically], is one of the famous historical one... the famous synthesis... the first total synthesis of a steroid. So, at that time... so, and that was done already in maybe around ’39 or ’40 and now I’m already almost 10 years later, I'm now in 1948, ’49 and there’d been no other total synthesis yet at that point.

Austrian-American Carl Djerassi (1923-2015) was best known for his work on the synthesis of the steroid cortisone and then of a progesterone derivative that was the basis of the first contraceptive pill. He wrote a number of books, plays and poems, in the process inventing a new genre, 'science-in-fiction', illustrated by the novel 'Cantor's Dilemma' which explores ethics in science.

Listeners: Tamara Tracz

Tamara Tracz is a writer and filmmaker based in London.

Tags: Cortisone, steroids, toad poison, Equilenin, University of Michigan, Werner Emmanuel Bachmann, Alfred Lawrence Wilds, Wayne Cole

Duration: 5 minutes, 14 seconds

Date story recorded: September 2005

Date story went live: 24 January 2008