Gallium(iii)-mediated dimerization routes for (5-phenyl-2-thienyl)cyclopropane-1,1-dicarboxylate

A selectivity-switched dimerization process for (5-phenyl-2-thienyl)cyclopropane-1,1-dicarboxylate under activation conditions with anhydrous Gaiii salts was developed. Using GaCl3 or Ga(NTf2)3 as catalysts, 3a,4,5a,6,7,8-hexahydro-5H-pentaleno[6a,1-b]thiophene and 5,6-dihydro-4H-cyclo-penta[b]thiophene derivatives can be selectively obtained as a result of ipso-type and [3+2]-annulation type dimerization. The crucial role of a phenyl substituent at position 5 of the thiophene ring and some regularities are discussed.     

A Novel Cathode Material for Cathodic Dehalogenation of 1,1‐Dibromo Cyclopropane Derivatives

Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives.     

Cyclopropyl iminium activation: reactivity umpolung in enantioselective organocatalytic reaction design

Trick the iminium! The concept of cyclopropyl iminium activation for the organocatalytic desymmetrization of meso-cyclopropylcarbaldehydes is presented. A combination of nucleophilic and electrophilic chlorinating reagents leads to a formal addition of Cl(2) across one of the cyclopropyl bonds giving access to 1,3-dichlorides in an enantioselective, catalytic fashion.