Prof. McBride, J. Michael, CHEM 125b, Freshman Organic Chemistry II, Spring 2011, YALE Open Courses: Yale University, Chemistry (Accessed 20/09/2014), http://oyc.yale.edu/chemistry/chem-125b/lecture-38 License: Creative Commons BY-NC-SA Discoverers of the structure and biological activity of steroid hormones won seven Nobel Prizes between 1927 and 1975. Many steps involved novel insights, others were based on lore from previous work in the area. The overall yield of such sequential syntheses is typically much lower than that of convergent syntheses. Practical syntheses of cortisone were based on modification of related steroids readily available from nature. Milestones in total synthesis include both purely intellectual work with natural products and commercially important synthesis of designed pharmaceuticals.