New photochromic switches based on helical alkenes can quickly and efficiently be accessed by Pd-catalyzed domino reactions using a modular approach; this allows a wide variability in product formation with the advantages of a convergent synthetic route. The alkenes have been synthesized in excellent enantioselectivity and their switching properties assessed by stimulation with nanosecond laser pulses at two different wavelengths in over 1000 switching cycles.

Alkynes are one of the most versatile functional groups as synthetic handles. They allow for a direct access to partially or fully substituted alkenes through difunctionalization reactions. A prominently utilized transformation for these sequences is the carbopalladation of alkynes, which can be followed by various termination steps such as aromatizations, dearomatizations, cross-coupling reactions, or pericyclic processes, amongst others. This Minireview provides an overview of the recent literature published in the field of carbopalladation chemistry, both with a focus on methodology as well as its application in the syntheses of complex molecular scaffolds, natural products, and functional molecules.

Helical tetrasubstituted alkenes (7) were obtained in a highly efficient way through a palladium-catalyzed domino-carbopalladation/CH-activation reaction of propargylic alcohols 6 in good to excellent yields. Electron-withdrawing- and electron-donating substituents can be introduced onto the upper and lower aromatic rings. The substrates (6) for the domino process were synthesized by addition of the lithiated alkyne (20) to various aldehydes (19); moreover, the substrates were accessible enantioselectively (in 95% ee) by reduction of the corresponding ketone using the Noyori procedure.

Fast and easy: Various helical tetrasubstituted alkenes were synthesized by a palladium‐catalyzed domino process. The domino process consists of a Sonogashira reaction, a carbopalladation, and a direct CH functionalization.

A detailed theoretical study of dimethyldioxirane-mediated epoxidations with a variety of differently substituted alkenes 3-21 is presented. Transition structures and activation barriers were determined in the gas phase and in acetone as solvent with the B3LYP/6-311+G(d) level of theory. Substituent effects were elucidated by frontier orbital analyses of the reacting species as well as by natural bond orbital (NBO) analysis of the transition structures. Epoxidations with alkenes carrying electron-donating groups such as OMe or NHAc commonly tend to have low activation energies and early transitions states, whereas using alkenes with electron-withdrawing moieties such as CN, SO2Me, CO2Me, CF3, CHO, and Cl higher activation barriers and late transition states are observed. In all cases a net charge transfer (CT) from the alkene to the dioxirane was observed substantiating the electrophilic character of dimethyldioxirane.