A new golden age for donor-acceptor cyclopropanes.
The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig (Germany) http://www.werzlab.de.
Tobias F
TF
Schneider
Johannes
J
Kaschel
Daniel B
DB
Werz
cycloaddition; cyclopropanes; donor-acceptor systems; ring enlargement; ring opening