1,1’-(Ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.

The interaction between hydronium ion and several crown ethers was studied via conductometry in nitromethane at 25 °C and 1H-NMR techniques. The stabilities of the resulting 1:1 complexes were determined from the conductance data and found to vary in the order DC18C6 > 18C6 > DB30C10 > DB24C8 > DB18C6 > ~B15C5 > DB21C7. For the first time, evidences for the formation of a 2:1 san...

We have synthesized a series of cis-6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of (±)-brazilin. A completely regio- and cis-diastereoselective intramolecular Friedel-Crafts epoxy-arene cyclization of 1-tetralone-derived glycidyl ethers catalyzed by Brønsted acids was used as the key step. Our worries concerning the formation of cis-trans product mixtures ...

Crown ethers are small, cyclic polyethers that have found wide-spread use in phase-transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein-crown ether co-crystals grown in the presence of 18-crown-6. We then employed biop...

1,1’-(ethane-1,2-diyl)dipyridinium bistribromide (edpbt) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.

ABSTRACT Ru-catalyzed synthesis of mixed alkyl-alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates. The catalytic systems for these reactions were generated from RuCl2(PPh3)3 and [RuCl2(1,5-COD)]x and phosphines [PPh3 or P(p-chlorophenyl)3] or SbPh3. Of particular importance is the almost quantitative eliminatio...

This review summarizes the new carbon-carbon bond construction methods based on the radical reaction of imine derivatives. The intermolecular carbon radical addition to oxime ethers proceeded smoothly in the presence of BF3.OEt2. A high degree of stereocontrol in the reaction of oxime ethers was achieved to give amino acid derivatives with excellent diastereoselectivities. The radical reaction ...