Halogen Bonding Initiated Difunctionalization of [1.1.1]Propellane via Photoinduced Polarity Match Additions.

Bicyclo[1.1.1]pentane (BCP), recognized as a bioisostere for para-disubstituted benzene, has gained widespread interest in drug development due to its ability to enhance the physicochemical properties of pharmaceuticals. In this work, we introduce a photoinduced, halogen bonding-initiated, metal-free strategy for synthesizing various BCP derivatives. This method involves the generation of nucleophilic α-aminoalkyl radicals via halogen-bonding adducts. These undergo selective radical addition to [1.1.1]propellane, yielding electrophilic BCP radicals that subsequently participate in polarity-matched additions, culminating in the difunctionalization of bicyclopentane. The versatility and practicality of this metal-free approach are underscored by its broad substrate scope, which includes late-stage functionalization and a series of valuable transformations, all conducted under mild reaction conditions.

Synthesis and structure of a complex of copper(I) with l-cysteine and chloride ions containing Cu12S6 nanoclusters.

The title hydrated copper(I)-l-cysteine-chloride complex has a polymeric structure of composition {[Cu16(CysH2)6Cl16]·xH2O} n [CysH2 = HO2CCH(NH3 +)CH2S- or C3H7NO2S], namely, poly[[tetra-µ3-chlorido-deca-µ2-chlorido-di-chlorido-hexa-kis-(µ4-l-cysteinato)hexa-deca-copper] polyhydrate]. The copper atoms are linked by thiol-ate groups to form Cu12S6 nanoclusters that take the form of a tetra-kis cubocta-hedron, made up of a Cu12 cubo-octa-hedral subunit that is augmented by six sulfur atoms that are located symmetrically atop of each of the Cu4 square units of the Cu12 cubo-octa-hedron. The six S atoms thus form an octa-hedral subunit themselves. The exterior of the Cu12S6 sphere is decorated by chloride ions and trichlorocuprate units. Three chloride ions are coordinated in an irregular fashion to trigonal Cu3 subunits of the nanocluster, and four trigonal CuCl3 units are bonded via each of their chloride ions to a copper ion on the Cu12S6 sphere. The trigonal CuCl3 units are linked via Cu2Cl2 bridges covalently connected to equivalent units in neighboring nanoclusters. Four such connections are arranged in a tetra-hedral fashion, thus creating an infinite diamond-like net of Cu12S6Cl4(CuCl3)4 nanoclusters. The network thus formed results in large channels occupied by solvent mol-ecules that are mostly too ill-defined to model. The content of the voids, believed to be water mol-ecules, was accounted for via reverse Fourier-transform methods using the SQUEEZE algorithm [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The protonated amino groups of the cysteine ligands are directed away from the sphere, forming N-H⋯Cl hydrogen bonds with chloride-ion acceptors of their cluster. The protonated carb-oxy groups point outwards and presumably form O-H⋯O hydrogen bonds with the unresolved water mol-ecules of the solvent channels. Disorder is observed in one of the two crystallographically unique [Cu16(CysH2)6Cl16] segments for three of the six cysteine anions.