Copper-Catalyzed Regioselective Ring-Opening Hydroamination of Methylenecyclopropanes.

A copper-catalyzed ring-opening hydroamination of methylenecyclopropanes with polymethylhydrosiloxane and O-benzoylhydroxylamines has been developed. The cyclopropane C-C bond cleavage occurs selectively at the more congested proximal position, and the corresponding homoallylamines are obtained in good to excellent yields. The umpolung electrophilic amination strategy with the hydroxylamine derivatives can provide a new reaction mode of methylenecyclopropanes in the catalytic hydroamination reaction.

Ligand-controlled regiodivergent Cu-catalyzed aminoboration of unactivated terminal alkenes.

A ligand-controlled regiodivergent Cu-catalyzed aminoboration of unactivated terminal alkenes with diboron reagents and hydroxylamines has been developed. The xantphos-ligated CuCl complex guides the boron and amino groups to the terminal and internal positions, respectively. On the other hand, the opposite regioisomers are selectively obtained under the N-heterocyclic carbene-based IPrCuBr catalysis. The two Cu catalysts can readily transform simple and abundant terminal alkenes into highly valuable ß-borylalkylamines regiodivergently.

Copper-catalyzed stereoselective aminoboration of bicyclic alkenes.

A copper-catalyzed aminoboration of bicyclic alkenes, including oxa- and azabenzonorbornadienes, has been developed. With this method, amine and boron moieties are simultaneously introduced at an olefin with exo selectivity. Subsequent stereospecific transformations of the boryl group can provide oxygen- and nitrogen-rich cyclic molecules with motifs that may be found in natural products or pharmaceutically active compounds. Moreover, a catalytic asymmetric variant of this transformation was realized by using a copper complex with a chiral bisphosphine ligand, namely (R,R)-Ph-BPE.

Highly stereoselective synthesis of (borylmethyl)cyclopropylamines by copper-catalyzed aminoboration of methylenecyclopropanes.

A Cu-catalyzed aminoboration of 1-methylenecyclopropanes with bis(pinacolato)diboron and O-benzoyl-N,N-dialkylhydroxylamines has been developed. The Cu catalysis provides a rapid and concise access to (borylmethyl)cyclopropylamines in a highly regio- and diastereoselective manner. The products obtained can be useful building blocks for the synthesis of potential antidepressants, trans-2-arylcyclopropylamine derivatives.