Four‐ and Sixfold Tandem‐Domino Reactions Leading to Dimeric Tetrasubstituted Alkenes Suitable as Molecular Switches

Abstract

A highly efficient palladium-catalyzed fourfold tandem-domino reaction consisting of two carbopalladation and two C-H-activation steps was developed for the synthesis of two types of tetrasubstituted alkenes 3 and 6 with intrinsic helical chirality starting from substrates 1 and 4, respectively. A sixfold tandem-domino reaction was also developed by including a Sonogashira reaction. 20 compounds with different substitution patterns were prepared with yields of up to 97 %. Structure elucidation by X-ray crystallography confirmed helical chirality of the two alkene moieties. Photophysical investigations of some of the compounds showed pronounced switching properties through light-controlled changes of their stereochemical configuration.

Excited-state relaxation of the solar cell dye D49 in organic solvents and on mesoporous Al2O3 and TiO2 thin films

“…In the second PSCP setup, [29][30][31][32] a UV-Vis multifilament supercontinuum spanning a wavelength range of 260-660 nm was generated in a translating 2 mm thick CaF 2 plate from the second harmonic (400 nm, 12 mJ pulse À1 ) of the fundamental beam of a regeneratively amplified titanium:sapphire system (Coherent Libra USP-HE, 800 nm, 50 fs, 3.5 mJ pulse À1 ).…”

A comprehensive picture of the ultrafast excited-state dynamics of retinal

“…Ultrafast broadband transient absorption experiments were carried out using UV-Vis pump -supercontinuum probe spectroscopy at 920 Hz repetition frequency. [17][18][19] All-trans retinal was excited by 400 nm pulses at every second laser shot (laser pulse fluence ca. 0.23 mJ cm À2 ).…”

Aluminum Chloride Promoted Cross‐Coupling of Trisubstituted Enol Phosphates with Organozinc Reagents En Route to the Stereoselective Synthesis of Tamoxifen and Its Analogues

“…Acyclic tetrasubstituted double bonds are important structural features of many compounds with varied applications, for instance as biologically active compounds. The increasing research into the stereoselective synthesis of tetrasubstituted alkenes clearly shows the importance of these compounds . The diversity of building blocks used for the synthesis of substituted alkenes has been reviewed .…”