The mechanism of the double intramolecular hetero‐Michael addition, a key reaction in the planned synthesis of the natural product calyculin C, has been studied by NMR. The cyclization follows Baldwin’s rules and proceeds first through a six‐membered ring closure (6‐endo‐dig), followed by a five‐membered ring cyclization (5‐exo‐trig).
- Michael addition
Rauhala, V., Nättinen, K., Rissanen, K., & Koskinen, A. M. P. (2005). The Reaction Mechanism of Spirocylization and Stereoselectivity Studies for the Calyculin C16–C25 Fragment. European Journal of Organic Chemistry, 2005(19), 4119-4126. https://doi.org/10.1002/ejoc.200500206