Synthesis of polyphenols and azafluorenones

The synthesis of 1,3,4,5-tetragalloylapiitol was accomplished in 7 steps. A direct synthesis of natural and unnatural ellagitannins were made using an intramolecular oxidative coupling. Different flavonols were synthesized via a novel base-mediated cyclization step, which was strategically different than previous ways to make flavonols. A three step synthesis of azaflureones was developed

A Convenient Synthesis of Type A Procyanidins

Type A procyanidins can be synthesized in good yields from the condensation of benzopyrilium salts 8 and either catechin or phloroglucinol

Efficient synthesis of fluorescent rosamines: multifunctional platforms for cellular imaging

Substituted rosamines are efficiently prepared through a new organometallic addition to an imine-substituted xanthone as a novel primary amine equivalent. The synthesis reduces the number of synthetic steps to the targeted rosamines, for convenient and facile access to potential libraries of rosamine dyes. The prepared rosamine derivatives represent unique multifunctional platforms that possess radiolabeling capability and fluorescence. Rosamines have (i) useful non-specific binding properties in mammalian cells and plant root hair, and (ii) positive uptake or binding properties in microbial systems

Specificity and ligand affinities of the cocaine aptamer: impact of structural features and physiological NaCl

The cocaine aptamer has been seen as a good candidate for development as a probe for cocaine in many contexts. Here, we demonstrate that the aptamer binds cocaine, norcocaine, and cocaethylene with similar affinities and aminoglycosides with similar or higher affinities in a mutually exclusive manner with cocaine. Analysis of its affinities for a series of cocaine derivatives shows that the aptamer specificity is the consequence of its interaction with all faces of the cocaine molecule. Circular dichroism spectroscopy and 2-aminopurine (2AP) fluorescence studies show no evidence of large structural rearrangement of the cocaine aptamer upon ligand binding, which is contrary to the general view of this aptamer. The aptamer’s affinity for cocaine and neomycin-B decreases with the inclusion of physiological NaCl. The substitution of 2AP for A in position 6 (2AP6) of the aptamer sequence eliminated the effect of NaCl on its affinities for cocaine and analogues, but not for neomycin-B, showing a selective effect of 2AP substitution on cocaine binding. The affinity for cocaine also decreased with increasing concentrations of serum or urine, with the 2AP6 substitution blunting the effect of urine. Its low affinities for cocaine and metabolites and its ability to bind irrelevant compounds limit the opportunities for application of this aptamer in its current form as a selective and reliable sensor for cocaine. However, these studies also show that a small structural adjustment to the aptamer (2AP exchanged for adenine) can increase its specificity for cocaine in physiological NaCl relative to an off-target ligand

Synthesis of polyphenols and azafluorenones

The synthesis of 1,3,4,5-tetragalloylapiitol was accomplished in 7 steps. A direct synthesis of natural and unnatural ellagitannins were made using an intramolecular oxidative coupling. Different flavonols were synthesized via a novel base-mediated cyclization step, which was strategically different than previous ways to make flavonols. A three step synthesis of azaflureones was developed.</p

Synthesis of Azafluorenone Antimicrobial Agents

A flexible synthesis of the azafluorenone alkaloids 1, 2, 3, and 4 is described.Reprinted (adapted) with permission from Journal of Natural Products, 73(11); 1967-1968. Doi: 10.1021/np100536a. Copyright 2010 American Chemical Society. </p

A Convenient Synthesis of Type A Procyanidins

Type A procyanidins can be synthesized in good yields from the condensation of benzopyrilium salts 8 and either catechin or phloroglucinol.This is article is from Molecules, 2009; 14(2); 807-815; Doi: 10.3390/molecules14020807. Posted with permission. </p

Efficient synthesis of fluorescent rosamines: multifunctional platforms for cellular imaging

Substituted rosamines are efficiently prepared through a new organometallic addition to an imine-substituted xanthone as a novel primary amine equivalent. The synthesis reduces the number of synthetic steps to the targeted rosamines, for convenient and facile access to potential libraries of rosamine dyes. The prepared rosamine derivatives represent unique multifunctional platforms that possess radiolabeling capability and fluorescence. Rosamines have (i) useful non-specific binding properties in mammalian cells and plant root hair, and (ii) positive uptake or binding properties in microbial systems.This is a manuscript of an article published as Kraus, George A., Tezcan Guney, Aaron Kempema, Joel M. Hyman, and Bahram Parvin. "Efficient synthesis of fluorescent rosamines: multifunctional platforms for cellular imaging." Tetrahedron Letters 55, no. 9 (2014): 1549-1551. DOI: 10.1016/j.tetlet.2014.01.067. Posted with permission.</p