The activation of p-bonds in diynyl esters has been investigated by using soft and hardLewis acids.Inthe case of the soft selenium Lewis acid PhSeCl, sequential activation of the alkyne bonds leads initially to an isocoumarin (1 equiv PhSeCl) and then to atetracyclic conjugated structure with the isocoumarin subunit fused to ab enzoselenopyran (3 equiv PhSeCl). Conversely,t he reaction with the hard Lewis acidic borane B(C 6 F 5 ) 3 initiates acascade reaction to yield acomplex p-conjugated system containing phthalide and indene subunits.

Azobenzenes are among the most extensively used molecular switches for many different applications. The need to tailor them to the required task often requires further functionalization. Cross-coupling reactions are ideally suited for late-stage modifications. This review provides an overview of recent developments in the modification of azobenzene and its derivatives by cross-coupling reactions.1 Introduction2 Azobenzenes as Formally Electrophilic Components2.1 Palladium Catalysis2.2 Nickel Catalysis2.3 Copper Catalysis2.4 Cobalt Catalysis3 Azobenzenes as Formally Nucleophilic Components3.1 Palladium Catalysis3.2 Copper Catalysis3.3 C–H Activation Reactions4 Azobenzenes as Ligands in Catalysts5 Diazocines5.1 Synthesis5.2 Cross-Coupling Reactions6 Conclusion

Two transition-metal-free methods to access substituted phenols via the arylation of silanols or hydrogen peroxide with diaryliodonium salts are presented. The complementary reactivity of the two nucleophiles allows synthesis of a broad range of phenols without competing aryne formation, as illustrated by the synthesis of the anesthetic Propofol. Furthermore, silyl-protected phenols can easily be obtained, which are suitable for further transformations.

Azobenzenes are important molecular switches that can still be difficult to functionalize selectively. A high yielding Pd-catalyzed cross-coupling method under mild conditions for the introduction of NHS esters to azobenzenes and diazocines has been established. Yields were consistently high with very few exceptions. The NHS functionalized azobenzenes react with primary amines quantitatively. These amines are ubiquitous in biological systems and in material science.

Ortho-functionalized azobenzenes are much sought after molecular switches, as they may be turned to absorb in the visible range of light and the (Z)-isomers can have high thermal half-lives. To...