We have prepared a variety of high molecular weight, thermally stable, blue-light-emitting random copolymers of 9,9-di-n-hexylfluorene by nickel(0)-mediated polymerization. The copolymers are readily soluble and easily processable from organic solvents. Both the polymer and electronic properties may be tuned by selection of comonomer structure. The electronic properties also vary with composition and film morphology. A blue-light-emitting device has been prepared using ionic salts for electrochemical doping.
The fungal metabolite (+)-11,11'-dideoxyverticillin A, a cytotoxic alkaloid isolated from a marine Penicillium sp., belongs to a fascinating family of densely functionalized, stereochemically complex, and intricate dimeric epidithiodiketopiperazine natural products. Although the dimeric epidithiodiketopiperazines have been known for nearly four decades, none has succumbed to total synthesis. We report a concise enantioselective total synthesis of (+)-11,11'-dideoxyverticillin A via a strategy inspired by our biosynthetic hypothesis for this alkaloid. Highly stereo- and chemoselective advanced stage tetrahydroxylation and tetrathiolation reactions, as well as a mild strategy for the introduction of the epidithiodiketopiperazine core in the final step were developed to address this highly sensitive substructure. Our rapid functionalization of the advanced molecular framework aims to mimic plausible biosynthetic steps and offers an effective strategy for the chemical synthesis of other members of this family of alkaloids.
On a fast track: The secondary metabolites (+)‐WIN 64821 and (−)‐ditryptophenaline have been synthesized in six and seven steps, respectively, from amino acid derivatives in a concise and enantioselective manner. The gram‐scale synthesis of key intermediates and the simultaneous introduction of vicinal quaternary stereocenters are described. The synthesis and structural confirmation of (−)‐1′‐(2‐phenylethylene)ditryptophenaline is also reported.
Biaryls constitute an important subunit found in medicinal agents, functional materials, and natural products. While the Suzuki reaction and related processes currently represent the method of choice for the construction of arene-arene bonds, the direct-coupling of two unfunctionalized arenes mediated by the addition of an oxidant represents a powerful alternative strategy for biaryl synthesis. This tutorial review describes recent progress in this rapidly developing field, focusing on intermolecular examples of selective arene oxidation strategies and metal-catalyzed oxidative cross-coupling via C-H activation.
The oxidation of 2-aryl tryptamines followed by a stereoselective rearrangement provides a versatile strategy for the synthesis of C3-quaternary oxindoles bearing a C3-aryl group. Treatment of optically active 2-aryl hydroxyindolenines with scandium trifluoromethanesulfonate in toluene at 110 degrees C leads to complete and stereoselective isomerization to the corresponding C3-aryl oxindoles which represent versatile intermediates for the synthesis of C3a-aryl hexahydropyrroloindoles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.