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Diarylfluoromethylsulfonium salts, alternatives to freons or advanced fluorinated building blocks, are bench stable and easy-to-use sources of direct fluoromethylene (:CHF) transfer to alkenes. These salts enabled development of a trans-selective monofluorinated Johnson–Corey–Chaykovsky reaction with vinyl sulfones or vinyl sulfonamides to access synthetically challenging monofluorocyclopropane scaffolds. The described method offers rapid access to monofluorinated cyclopropane building blocks with further functionalization opportunities to deliver more complex synthetic targets diastereoselectively.

An investigation of the properties and reactivity of fluoromethylsulfonium salts resulted in the redesign of the reagents for fluoromethylene transfer chemistry. The model reaction, fluorocyclopropanation of nitrostyrene, turned out to be a suitable platform for the discovery of more streamlined fluoromethylene transfer reagents. The incorporation of halides on one aryl ring increased the reactivity, and 2,4-dimethyl substitution on the other aryl ring provided a balance between the reactivity/crystallinity of the reagent as well as the atom economy. The utility of new reagents was demonstrated by the development of an efficient fluorocyclopropanation protocol to access a range of monofluorinated cyclopropane derivatives.

Aryl substituted 2,2,2-trifluorodiazoethanes undergo rhodium(II)-catalysed insertion reactions with tin hydrides affording the corresponding α-(trifluoromethyl)benzyl stannanes. This reactivity contrasts with that of diazo esters which predominantly afford CH2 reduction products in the presence of tin hydrides. The first example of asymmetric insertion into tin hydrides using diazo compounds is also described. In addition, this system extends to asymmetric germanium hydride and silane insertion.

This study describes synthetic efforts towards the molecular Borromean link consisting of three unequal rings. The design and strategy involve step by step construction of a ruthenium(II) templated ring-in-ring complex doubly threaded with endocyclic ligands ready for the macrocyclization. The control over the topology is achieved by using specially designed directional building blocks based on 2,2′:6′,2′′-terpyridine. Preliminary macrocyclization attempts utilizing the copper-mediated Eglington reaction provide the mass spectrometric evidence consistent with the ruthenium(II) complex of the molecular Borromean link.

This work was supported by the Swiss National Science Foundation. A kinetically directed, stepwise approach towards molecular Borromean links enabled the isolation and structural characterization of synthetic intermediates along the way. Here we report the synthesis and crystal structures of three flexible macrocyclic intermediates and a new ring-in-ring complex, anchored together through ruthenium(ii) centers, which contains open terpyridine caps in the inner Ring II. Terpyridines circumvent the conformational cis/trans limitations of bipyridines and the new ring-in-ring complex forms tetrametallic complexes with Zn(ii), Pt(ii) and Ru(iii) metal ions. Analysis of the four macrocyclic structures provides a good foundation for the conformational flexibility in these complexes and demonstrates the robust applicability of the terpyridine design elements towards the engineered synthesis of ring-in-ring topologies. Publisher PDF

Copper-catalyzed Si-H, B-H, P-H, S-H, and N-H insertion reactions of 2,2,2-trifluoro-1-diazoethane and 1-aryl 2,2,2-trifluorodiazoethanes generated a large number of new fluorine-containing chemical entities for medicinal chemists. With selected Si-H and B-H insertion reactions, we demonstrate successful extension to asymmetric catalysis.