Dual Control of the Selectivity in the Formal Nucleophilic Substitution of Bromocyclopropanes en Route to Densely Functionalized, Chirally Rich Cyclopropyl Derivatives

Preparation of Chiral Enantioenriched Densely Substituted Cyclopropyl Azoles, Amines, and Ethers via Formal SN2′ Substitution of Bromocylopropanes

Enantiomerically enriched cyclopropyl ethers, amines, and cyclopropylazole derivatives possessing three stereogenic carbon atoms in a small cycle are obtained via the diastereoselective, formal nucleophilic substitution of chiral, non-racemic bromocyclopropanes. The key feature of this methodology is the utilization of the chiral center of the cyclopropene intermediate, which governs the configuration of the two adjacent stereocenters that are successively installed via 1,4-addition/epimerization sequence.

Hydrogermylation of Alkenes via Organophotoredox-Initiated HAT Catalysis

This Letter discloses the straightforward hydrogermylation of olefins under visible-light organophotoredox-initiated HAT catalysis conditions to yield primary and secondary alkyl germanes at room temperature. The protocol is operationally simple, metal-free, and tolerant of various functional groups. The synthesized alkyl germanes proved to be highly robust toward acidic, basic, or oxidizing conditions and chemical transformations of C_sp²-GeEt₃ or C_sp²-BPin functionalities in their presence.

Intramolecular nucleophilic addition of carbanions generated from N-benzylamides to cyclopropenes

An unusual reaction is described, involving a formal intramolecular nucleophilic substitution of bromocyclopropanes with nitrogen ylides generated in situ from N-benzyl carboxamides. It is shown that this reaction involves cyclopropene intermediates and allows for the facile and expeditious preparation of 3-azabicyclo[3.1.0]hexan-2-one scaffolds.

Directed nucleophilic addition of phenoxides to cyclopropenes

The alkali metal-templated addition of aryloxides across the double bond of non-conjugated cyclopropenes is described. High cis-selectivity is achieved through a directing effect of a strategically positioned carboxamide functionality.

Templated assembly of medium cyclic ethers via exo-trig nucleophilic cyclization of cyclopropenes

A novel method for the assembly of medium heterocycles via an intramolecular nucleophilic addition to cyclopropenes is described. The exo-trig nucleophilic cyclizations were shown to proceed very efficiently and in a highly diastereoselective fashion affording cis-fused bicyclic products possessing 7 to 10-membered medium rings; starting from a diastereomeric mixtures of bromocyclopropanes.

Synthesis of 1,5-Dioxocanes via the Two-Fold C-O Bond Forming Nucleophilic 4+4-Cyclodimerization of Cycloprop-2-en-1-ylmethanols

An efficient [4+4] cyclodimerization of cyclopropenemethanols operating via a two-fold strain release-driven addition of alkoxides across the double bond of cyclopropenes was investigated. This chemo- and diastereoselective transformation provided previously unknown 2,7-dioxatricyclo[7.1.0.0^4,6]decane scaffolds.

One-pot synthesis of GABA amides via the nucleophilic addition of amines to 3,3-disubstituted cyclopropenes

A one-pot synthesis of various GABA amides has been demostrated, employing the nucleophilic addition of primary and secondary amines across the double bond of cyclopropene-3-carboxamides, followed by ring-opening of the resulting donor-acceptor cyclopropanes and subsequent in situ reduction of enamine (imine) intermediates.