An Efficient Synthesis of [n]Cycloparaphenylenes (n = 9, 12, 15) via the Self-Assembly into Macrocyclic Gold(I)-Oligophenylene Complexes Based on Dynamic Au–C σ-Bonds

The transmetalation of the digold(I) complex [Au2Cl2(Cy2PCH2PCy2)] with oligophenylene diboronic acids gave the triangu-lar macrocyclic complexes [Au2(C6H4)x(Cy2PCH2PCy2)]3 (x = 3, 4, 5) with yields of over 70%. A series of [n]cycloparaphenylenes (n = 9, 12, 15) was isolated in 78–88% yield via the oxidative chlorination of the macrocyclic gold complexes. A kinetics study employing two acyclic dinuclear gold(I) complexes, [Au2R2(Cy2PCH2PCy2)] (R = Ph and/or C6H4-4-F), revealed that an intermolecular Au(I)–C σ-bond-exchange reaction proceeded. These results indicate that the trian-gular complexes were obtained selectively via reversible intermolecular Au(I)–C σ-bond exchanges. By reacting two different oligophenylene diboronic acids with the digold(I) complex, a mixture of macrocyclic complexes incorporating different oli-gophenylene linkers was formed. The oxidative chlorination of this mixture gave [n]cycloparaphenylenes with various num-bers of phenylene units.

Expeditious Preparation of N-Fmoc 2-Aminoethanesulfonyl Chlorides with Functionalized 1-Substituents

Aim and Objective: [(9H-Fluoren-9-yl)methoxy]carbonyl (Fmoc)-protected 2-aminoethanesulfonyl chlorides with various functionalized 1-substituents may be of use as building blocks for the Fmoc strategic synthesis of sulfonopeptides. Materials and Method: Fmoc-protected 2-aminoethanesulfonyl chlorides with different functionalized 1- substituents were synthesized via radical addition of N-Fmoc allylamine and xanthates with functionalized Ssubstituents, and subsequent oxidative chlorination with N-chlorosuccimide/HCl. Results: Fmoc-protected 2-aminoethanesulfonyl chlorides with different functionalized 1-substituents were synthesized via radical addition and subsequent oxidative chlorination. The mechanism on the oxidative chlorination is proposed. Conclusion: The current method is an expeditious, convenient, and practical method for the synthesis of Fmocprotected 2-aminoethanesulfonyl chlorides with different functionalized 1-substituents in good to excellent yields.

Oxidation of 3β-Acetoxy-21β-acetyl-20β,28-epoxy-18α,19βH-ursane into Novel gem-Chloronitro- and 1,2,4,5-tetraoxane derivatives

The first oxidative transformations of 3β-acetoxy-21β-acetyl-20β,28-epoxy-18α,19β H-ursane at the 21β-acetyl reaction center were performed. Ursane-type 1,2,4,5-tetraoxanes were synthesized by acid-catalyzed peroxy-condensation with cyclohexanone bis-hydroperoxide, and oxidation of the C(28)H2 group to C(28)=O was also observed. The ursane-bearing exogenous oximino-moiety was formed as a mixture of syn- and anti-isomers (1:1). Oxidative chlorination of oxime via NaCl/oxone led to the diastereomeric mixture of novel ( R) and ( S)- gem-chloronitro-derivatives (1:1). The stereochemistry of oximino- and gem-chloronitro- derivatives was established through X-ray analysis and NMR spectroscopy.