The synthesis of cyclopropanes and cyclopropane-containing compounds has been the subject of countless investigations for decades. The cyclopropyl group is commonly found in natural products and pharmaceuticals, so routes to this moiety are still under active study today. There are a wide range of methods to synthesize cyclopropanes, including named reactions like the Simmons-Smith reaction(1), and general classes of reactions like ring contraction of diazo compounds. 

 

    Starting from the first published synthesis of cyclopropane(2), this talk will cover the conditions, mechanisms, selectivity, and modern applications of three main types of cyclopropanation reactions- reactions of carbene-like reagents with alkenes, addition of methylene to olefins via ylides(3), and ring contractions of pyrazolines. Comparisons between these reactions in current syntheses(4) will be made and examples of recent applications will be discussed. 

 

1. Simmons, H. E.; Smith, R. D. J. Am. Chem. Soc. 1958, 80, 5323-5324.

2. Freund, A. Journal für Praktische Chemie. 1882, 23, 367-377.

3. Li, A.-H.; Dai, L.-X. Chem. Rev. 1997, 97, 2341-2372.

4. Ebner, C.; Carreira, E. M. Chem. Rev. 2017, 117, 11651-11679.