Artificial holoenzymes for benzoin condensation using thiazolio-appended β-cyclodextrin dimers

Synthesis of benzoin under supramolecular catalysis involving cyclodextrins in water: application for the preparation of the antiepileptic drug phenytoin

Among the cyclodextrins screened for the synthesis of 2-hydroxy-1,2-diphenylethanone (benzoin) in water, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) exhibited the highest yield in the benzoin condensation reactions, and HP-β-CD can be recycled several times with little loss of activity through the addition of fresh VB₁. As an example of supramolecular catalysis, the methodology was applied to the “green” synthesis of the antiepileptic drug phenytoin through benzoin condensation, oxidation, and cyclization reactions in the presence of HP-β-CD, without the use of any harmful organic solvent. Moreover, the complexation behaviors of HP-β-CD with benzaldehyde and intermediates were studied by UV-vis and 2D-ROESY NMR spectroscopies to reveal the plausible mechanisms of the reactions, and HP-β-CD did not act as a simple phase transfer agent.

Benzoin was synthesized using cyclodextrins as phase transfer catalysts. As an example of supramolecular catalysis, the methodology was applied to the “green” synthesis of the antiepileptic drug Phenytoin in the presence of HP-β-CD.

Microwave Assisted Benzoin Condensation using Thiamine as Catalyst

α-Hydroxyketones were prepared in appreciable yields at a very high speed, (by the benzoin condensation) under microwave irradiation using a catalytic amount of thiamine hydrochloride, from various aromatic as well as heteroaromatic aldehydes. They can be used as intermediates in NCE synthesis.

One-pot synthesis of tetrahydro-4H-chromenes by supramolecular catalysis in water

Tetrahydro-4H-chromenes were synthesizedviaan efficient one-pot three-component protocol by supramolecular catalysis with β-cyclodextrin in water.

On the synthesis of new amphiphilic entities by the succinic coupling of β-cyclodextrins to calixarenes

Novel molecules, composed of a β-cyclodextrin coupled via a succinic diamide linker to di-n-octyl-calix[4]arene monocrown-6 or to biscrown-6-calix[4]arene, were synthesized by two independent routes: from mono-6′-deoxy-6′-amino-β-cyclodextrin, and from tetraaminocalix[4]arene derivatives. Key words: β-cyclodextrin–calix[4]arene coupling, aminosuccinate-β-CD, aminosuccinate-calix[4]arene, octyloxy-calix[4]arene–monocrown-6, calix[4]arene–biscrown-6.

The first successful crystallographic characterization of a cyclodextrin dimer: efficient synthesis and molecular geometry of a doubly sulfur-bridged beta-cyclodextrin

Beta-cyclodextrin is transannularly disulfonylated at the 6(A)- and 6(B)-positions, and then converted to the corresponding 6(A),6(B)-diiodide and 6(A),6(B)-dithiol. Cross-coupling of the latter two species yields a single head-to-head-coupled beta-cyclodextrin dimer 5 with two sulfur linkers at adjacent 6-methylene carbons. NMR and X-ray analysis revealed the trans-type ("aversive") linkage of both beta-cyclodextrin units. In the solid-state structure of 5.5 MeOH.23 H(2)O, the undistorted cyclodextrin macrocycles feature almost parallel ring planes pointing away from each other, leaving 5 with a "handcuff-like" appearance of approximate C(2) symmetry. This work represents the first successful crystallographic study on a cyclodextrin dimer.