Current Organic Chemistry - Volume 17, Issue 14, 2013

Gating in host-guest chemistry refers to conformational changes that occur in response to some stimulus, resulting in opening or closing of a physical barrier that controls access to the host. Gating due to conformational changes of protein loops is common in enzyme catalysts: the binding of a substrate in an enzyme often involves the closing of a protein loop to bind the substrate, a type of gating [1]. Cram’s pioneering wor Read More

The transport of ions across molecular cages that mimic the behavior of bio-membranes has been of wide interest to researchers, but the synthesis of cage or capsular entities with ion transport properties is often challenging. A variety of molecular building blocks, such as calixarenes or cavitands, has been employed to study encapsulation and ion-transport properties. Recently, we have studied the transport of ions int Read More

This review provides a detailed overview on the research carried out in self-assembled supramolecular capsules enabling encapsulation of transition metals within their inner space. The supramolecular assemblies discussed are based on cationic/anionic interactions between cone-shaped building blocks, derived from quaternary ammonium and sulfonated salts, which upon assembly give rise to closed cavitands. Fu Read More

The reaction mechanism for the hydrogenation of norbornadiene (nbd) catalysed by bis-norbornadiene rhodium(I) [Rh(nbd)2]+ complex has been studied by means of DFT based methods, in the absence and in the presence of a self-folding octaamide cavitand. Formation of three products, norbornene, nortricyclene and a dimer is discussed. When the metal complex is encapsulated inside the cavitand, the steric crowding pr Read More

In recent years, asymmetric reactions catalyzed by the carbohydrate-based catalysts are the most intensively studied as they have been recognized as versatile starting materials for chiral auxiliaries, reagents, ligands and organocatalysts. The design and finetuning of carbohydrate-based catalysts is facilitated by the multiple functional groups present within this class of compounds. This strategy has provided unique Read More

Phosphoesters are abundant in carbohydrate structures, yet their chemical reactivity is less well known than that of nucleoside phosphoesters. Both classes of compounds contain sugar bound phosphoesters, but structural versatility of carbohydrates means that the reactivity range is wider, and reaction mechanisms not feasible in nucleic acid chemistry, are possible. Sugar phosphates, as well as their phosphodiester and phosph Read More

Diverse natural product-like N-benzyl cinnamamides were prepared by condensation of trans-cinnamic acid with substituted benzylamines in the presence of boric acid as catalyst. The further evaluation of this amides as a substrates of the bromo-arylation reaction, in the presence of N-bromosuccinimide (NBS) as the halogen source and under the catalysis of Yb(OTf)3, generate a different types of N-substituted amides: Read More

Chiral chromans and flavanones derivatives are widely exist in plants, asymmetric synthesis of biological active chiral flavanone and chromanone derivatives is a valuable research field. A chroman derivatived (+)-(S,R,R,R)-Nebivolol (β1-adrenergic receptor blocker) has been synthesized by natural chiron and sulfoxide-directed method recently. Enantioselective method for the synthesis of flavanones and chromanones by the Read More

A new proline derivative of (S)-5-prolylamide-triazole was synthesized and evaluated as an organocatalyst for the direct asymmetric aldol reaction of acetone with aromatic aldehydes under no extra solvent. At room temperature and in the absence of extra solvent, 15 mol% catalyst efficiently catalyzed the direct asymmetric aldol reactions to give aldol adducts, with modest enantiomeric excess (ee) of up to 74%. The titled rea Read More