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Please login to access the full content or check if you have access via Method 3: Rearrangement of Cyclopropylcarbenes

DOI: 10.1055/sos-SD-043-00415

Krueger, A.Science of Synthesis, (200843534.

The rearrangement of a cyclopropylcarbene also proceeds over a coarctate transition state. Concerning the complexity of the transition state, the fragmentation of cyclopropylcarbenes is among the simplest examples for coarctate reactions. It has been well studied since its discovery in 1960.[‌267‌] It leads to the respective pair of an alkene and an alkyne in the case of monocyclic starting compounds 158 and to linear enynes in the case of bicyclic starting compounds (Scheme 74).[‌263‌] Fragmentation is favored over ring expansion in the case of five-, six-, and seven-membered rings bridging the cyclopropyl ring. This is due to the fact that these ring sizes lead to exclusive endo arrangement of the cyclopropylcarbene. Larger rings allow for more steric flexibility.

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