silica-grafted n-propyl-diaza-15-crown-5 (sgpdc) with immobilized palladium nanoparticles was found as an efficient heterogeneous catalytic system for the heck and suzuki coupling reactions and satisfied results were obtained. different derivatives of aryl halides and alkenes under the heck reaction were converted to the corresponding products with good efficiency. the presence of electron-dona...

The first total synthesis of the dimeric alkaloid pigment scytonemin is described. The key transformations in its synthesis from 3-indole acetic acid are a Heck carbocyclization and a Suzuki-Miyaura cross-coupling, orchestrated in a stereospecific tandem fashion, followed by a biosynthetically inspired oxidative dimerization. The tandem sequence generates a tetracyclic (E)-3-(arylidene)-3,4-dih...

A sequence of acetamide directed oxidative Heck reaction and deacetylation-diazotation-Heck coupling allows the traceless removal of the acetamide group and its dual exploitation as a catalyst directing group and a leaving group.

Coumarins are associated with a variety of pharmacological activities which have led to the synthesis of numerous derivatives. However, no general method for determination of the absolute configuration of chiral coumarins is known. This has now been achieved for a series of dihydrofuroangelicins bearing a variety of C-8 substituted double bonds, synthesized in the racemic form and resolved thro...

Short alkyl chain Heck (type) reactions, especially methyl Heck reactions, are a difficult aspect of the alkyl Heck reaction. To provide a solution to this problem, iron-catalyzed methyl, ethyl and propyl Heck reactions were developed using readily available alkyl peroxides as alkyl sources. The reaction conditions were mild, clean, and easy to handle. No additive was needed, and no hazardous w...

In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organized based on the type of structures used in the assembly of the C-glycosides (also called C-nucleosides) with the following subsections: pyrimidine C-nucleosides, purine C-nucleosides, and monocyclic, bicyclic, and tetracyclic C-nucleosides. The reagents and conditions used for conducting the Heck cou...

The rate of the Pd/C catalyzed Heck coupling of Ar-I with CH(2)=CH-R is accelerated tenfold by the presence of Aliquat 336 (A336), a well known phase transfer catalyst, and an ionic liquid. Both when conducted in A336 as solvent, and in an isooctane/A336/aqueous triphasic mixture, the Heck reaction of aryl iodides with electron deficient olefins, catalyzed by Pd/C, proceeds with high yields and...

Owing to their versatile (opto)electronic properties, conjugated polymers have found application in several organic electronic devices. Cross-coupling reactions such as Stille, Suzuki, Kumada couplings, and direct arylation proved be effective for synthesis. More atom-efficient oxidative polymerization has also been reported making homopolymers. However, growing interest toward donor-acceptor l...

INVESTIGATIONS made by Motokawa and Mita (1942), Adrian (1945), Gastaut (1949), Johnson (1949), Schubert and Bornschein (1952), Armington (1952), Armington, Johnson, and Riggs (1952), Bornschein (1953), Burian (1954), and Auerbach and Burian (1955), and by other investigators, have revealed that-under suitable conditions of examination-the human electroretinogram (ERG) normally consists of a ph...