Oxidative radical ring-opening/cyclization of cyclopropane derivatives

Abstract

The ring-opening/cyclization of cyclopropane derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be of sufficient interest for the scientific community to further advance the application of oxidative radical strategies in the ring-opening/cyclization of cyclopropane derivatives.

Iron catalysts with N-ligands for carbene transfer of diazo reagents

“…[16][17][18][19][20] The high chemical reactivity of cyclopropanecontaining species is due to the high bond-strain of the threemembered ring; many other valuable compounds can be easily synthesized by inducing ring-opening reactions of the cyclopropyl fragment. [21][22][23][24][25][26] Frequently, the cleavage of the cyclopropyl carbon-carbon bond is also a way, in which active drug molecules produce their pharmacological effects. 16 The cyclopropanation reaction, which takes place by transferring the carbene unit from the diazo compound to the double bond, 27 can occur with a specific diastereoselectivity and, if conducted in the presence of a chiral promoter, a pair of enantiomers are obtained for each diastereomer (Scheme 1).…”

Ferrocenium Cations as Catalysts for the Etherification of Cyclopropyl‐Substituted Propargylic Alcohols: Ene‐yne Formation and Mechanistic Insights

“…Taking the data in Table together, preliminary results are somewhat inconclusive. The reaction may proceed through a radical mechanism: the cyclopropyl substrate ring‐opens to the ene‐yne product. Cobaltocenium hexafluorophosphate, which does not act as a one‐electron oxidant but possibly as a Lewis acid, is catalytically inactive.…”

“…As such, a radical mechanism appears unlikely. Some radical ring‐opening mechanisms were reported to proceed under oxidative conditions with an oxidant present in stoichiometric amounts . We employed FcPF 6 (potentially an oxidant) in catalytic amounts.…”

DFT Study of the Structural, Electronic, Bonding Nature, NBO Analysis, and Thermodynamic Properties of Halogenated (F, Cl, Br) and Heteroatom (O, N, S) doped Cyclopropane

“…The electron donor orbital, acceptor orbital, and interacting stabilizing energy resulting from 2 order perturbation theory obtained from NBO calculation. The higher the stabilization energy (2) value the higher is the interaction between the electron filled and unfilled orbitals i.e the greater donating tendency from electron donors to electron acceptors and the greater the extent of conjugation of the whole system. Delocalization of electron density between occupied Lewis-type (bond or lone pair) NBO orbitals and formally unoccupied (antibond or Rydberg) non-Lewis NBO orbitals corresponds to a stabilizing donor-acceptor interaction [17][18][19].…”

“…Cyclopropane is a cycloalkane molecule with the molecular formula 3 6 , which consists of 3 carbon atoms joined together to form a ring, with each carbon atom bearing two hydrogen atoms resulting in 3ℎ molecular symmetry [1][2][3]. The unique reactivity of cyclopropanes due to the high level of strain offers considerable utility in organic synthesis.…”