Environmental concerns in the 1970’s led to the increase in the significance of green chemistry, which peaked in the 1990’s. Both industry and academia have been splicing some emphasis on organic reactions that can be performed more efficiently, safely and preventing unnecessary waste, using changes such as use of aqueous medium or solvent free reactions, catalytic methods and microwave synthesis. Calarene is a sesquiterpenes from the carene family, which was synthesized by Coates and Shaw in 1970. The overall synthesis resulted in about 24% overall yield. Some of the reactions used included the Robinson annulation, pyrolysis, and hydrogenation where some of which have greener versions published, while others remain unsafe. Particularly, pyrolysis reactions may not be able to be performed into a traditional undergraduate laboratory. A couple of the material used in their synthesis were methyllithium and hydrazine hydrate which list amongst their hazards forming explosive peroxides, extremely corrosive and may catch fire spontaneously in air. This project focuses on the development of greener synthesis of calarene with comparison to established methods for comparison, using primarily reactions traditionally learned in Organic Chemistry, such as the Wittig and Diels Alder reactions. These reactions have been chosen because they utilize concepts tied to the 12 –principles of green chemistry. Based on our proposed methodology the overall theoretical yield for the synthesis is about 55%. The focus is to develop a semester long multi-week synthesis towards calarene for the second semester of the organic laboratory that emphasizes green chemistry at each step. Additionally, the lab provides experience towards a total synthesis of a small molecule.

Development of a green multi-week synthesis for the organic lab: Total synthesis towards calarene

251st National Meeting (2016)

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