A novel catalytic synthesis of 3,3'-(arylmethylene)-bis-(4-hydroxy-2H-chromene-2-one) derivatives from a tandem condensation reaction of 4-hydroxycoumarin and aromatic aldehydes has been developed. The reaction occurs in water in the presence of Melamine trisulfonic acid as catalyst to give the corresponding products in good to high yields. This green approach has several advantages such as sho...

a novel catalytic synthesis of 3,3'-(arylmethylene)-bis-(4-hydroxy-2h-chromene-2-one) derivatives from a tandem condensation reaction of 4-hydroxycoumarin and aromatic aldehydes has been developed. the reaction occurs in water in the presence of melamine trisulfonic acid as catalyst to give the corresponding products in good to high yields. this green approach has several advantages such as sho...

A novel transition-metal-free direct synthesis of 3-substituted isocoumarin from 4-hydroxycoumarin and a benzyne precursor is developed. This synthetic strategy proceeds via C-O and C-C bond cleavage as well as C-O and C-C bond formations in a single reaction vessel by simple treatment with CsF in the absence of catalyst. This methodology affords moderate to good yields of 3-substituted isocoum...

A variety of enantioenriched naphthoquinones have been synthesized in high yields and excellent enantioselectivities (up to >99% ee) using a bifunctional chiral bis-squaramide catalyzed conjugate addition of 2-hydroxy-1,4-naphthoquinone to 2-enoylpyridines. Some of the Michael products have been successfully converted into various enantioenriched pyranonaphthoquinone derivatives. The protocol i...

5-Tripropargylamine-2'-deoxyuridine (1 a) containing two terminal triple bonds was synthesized by a Pd-assisted Sonogashira cross-coupling reaction and was subsequently converted into the corresponding phosphoramidite building block (9) and employed in solid-phase oligonucleotide synthesis. T(m) experiments demonstrate that the presence of covalently attached branched tripropargylamine residues...

We report in this work successful isolation and cryopreservation of enterocytes from human small intestine. The enterocytes were isolated by enzyme digestion of the intestinal lumen, followed by partial purification via differential centrifugation. The enterocytes were cryopreserved directly after isolation without culturing to maximize retention of in vivo drug-metabolizing enzyme activities. ...

The status of hepatic function can be altered by diverse influences. Multiple functional processes are measurably affected by several extrinsic toxic agents (typhoid toxin, chloroform, yellow phosphorus) as well as by a large number of pathological disorders. After exposure to toxins, in obstructive jaundice, in cirrhotic processes, in intrahepatic tumors and the like, either anatomical disrupt...