Multivalent glibenclamide to generate islet specific imaging probes.

The monitoring of diabetes mellitus, as it develops and becomes clinically evident, remains a major challenge for diagnostic imaging in clinical practice. Here we present a novel approach to beta-cell imaging by targeting the sulphonylurea receptor subtype 1 (SUR1), using multivalent derivatives of the anti-diabetic drug glibenclamide. Since glibenclamide has a high affinity for SUR1 but does not contain a suitable functional group to be linked to an imaging probe, we have synthesized 11 glibenclamide derivatives and evaluated their affinity to SUR1 in MIN6 cells.

Synthesis of Substituted Quinolines by the Electrophilic Cyclization of N-(2-Alkynyl)anilines.

A wide variety of substituted quinolines are readily synthesized under mild reaction conditions by the 6-endo-dig electrophilic cyclization of N-(2-alkynyl)anilines by ICl, I(2), Br(2), PhSeBr and p-O(2)NC(6)H(4)SCl. The reaction affords 3-halogen-, selenium- and sulfur-containing quinolines in moderate to good yields in the presence of various functional groups. Analogous quinolines bearing a hydrogen in the 3-position have been synthesized by the Hg(OTf)(2)-catalyzed ring closure of these same alkynylanilines.

Intracellular reactive oxygen species in monocytes generated by photosensitive chromophores activated with blue light.

Objectives: Disinfection of the tooth pulp-canal system is imperative to successful endodontic therapy. Yet, studies suggest that 30-50% of current endodontic treatments fail from residual bacterial infection. Photodynamic therapy using red-light chromophores (630 nm) to induce antimicrobial death mediated by generated reactive oxygen species (ROS) has been reported, but red-light also may thermally damage resident tissues.

Polymeric photosensitizer prodrugs for photodynamic therapy.

A targeting strategy based on the selective enzyme-mediated activation of polymeric photosensitizer prodrugs (PPP) within pathological tissue has led to the development of agents with the dual ability to detect and treat cancer. Herein, a detailed study of a simple model system for these prodrugs is described. We prepared "first-generation" PPP by directly tethering the photosensitizer (PS) pheophorbide a to poly-(L)-lysine via epsilon amide links and observed that by increasing the number of PS on a polymer chain, energy transfer between PS units improved leading to better quenching efficiency.

Tailoring protease-sensitive photodynamic agents to specific disease-associated enzymes.

We have developed novel polymeric photosensitizer prodrugs (PPPs) for improved photodynamic therapy. In PPPs, multiple photosensitizer units are covalently coupled to a polymeric backbone via protease-cleavable peptide linkers. These initially non-photoactive compounds become fluorescent and phototoxic after specific enzymatic cleavage of the peptide linkers and subsequent release of the photosensitizer moieties.

Aryl to aryl palladium migration in the Heck and Suzuki coupling of o-halobiaryls.

A novel 1,4-palladium migration between the o- and o'-positions of biaryls has been observed in organopalladium intermediates derived from o-halobiaryls. The organopalladium intermediates generated by this migration have been trapped either by a Heck reaction employing ethyl acrylate or by Suzuki cross-coupling using arylboronic acids. This palladium migration can be activated or deactivated by choosing the appropriate reaction conditions.

An aryl to imidoyl palladium migration process involving intramolecular C-H activation.

Biologically interesting fluoren-9-one and xanthen-9-one derivatives have been prepared by a novel aryl to imidoyl palladium migration, followed by intramolecular arylation. The fluoren-9-one synthesis appears to involve both a palladium migration mechanism and a C-H activation process proceeding through an unprecedented organopalladium(IV) hydride intermediate. The results from deuterium labeling experiments are consistent with the proposed dual mechanism.

Fluorescence diagnosis using enzyme-related metabolic abnormalities of neoplasia.

Early cancer diagnosis is of the most crucial factors determining proper patient management and long-term survival. Thus, there is considerable interest in developing more reliable methods for cancer diagnosis. Fluorescence diagnosis using metabolic alterations of neoplasia has emerged as a powerful new biomedical tool.

5-Aminolevulinic acid derivatives in photomedicine: Characteristics, application and perspectives.

The introduction of lipophilic derivatives of the naturally occurring heme precursor 5-aminolevulinic acid (5-ALA) into photomedicine has led to a true revival of this research area. 5-ALA-mediated photodynamic therapy (PDT) and fluorescence photodetection (FD) of neoplastic disease is probably one of the most selective cancer treatments currently known in oncology. To date, this method has been assessed experimentally for the treatment of various medical indications.

Synthesis of polycyclic aromatics and heteroaromatics via electrophilic cyclization.

[reaction: see text] A variety of substituted polycyclic aromatics are readily prepared in good to excellent yields under very mild reaction conditions by the reaction of 2-(1-alkynyl)biphenyls with ICl, I(2), NBS, and p-O(2)NC(6)H(4)SCl. This methodology readily accommodates various functional groups and has been successfully extended to systems containing a variety of polycyclic and heterocyclic rings.

Synthesis of substituted quinolines by electrophilic cyclization of N-(2-alkynyl)anilines.

Quinolines substituted in the 3-position by an iodo or phenylseleno group are readily prepared in good to excellent yields by the reaction of propargylic anilines with appropriate electrophiles under mild reaction conditions. [reaction: see text]

Synthesis of fused polycycles by 1,4-palladium migration chemistry.

Novel palladium migration/arylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that these palladium-catalyzed C-H activation reactions parallel electrophilic aromatic substitution.

Synthesis of polycyclic aromatic iodides via ICl-induced intramolecular cyclization.

The reaction of 2-(arylethynyl)biphenyls with ICl at -78 degrees C affords substituted polycyclic aromatic iodides in good to excellent yields. The aryl substituents can be either electron-donating or electron-withdrawing groups such as OMe, Me, CHO, CO(2)Et or NO(2) groups. This chemistry has been successfully extended to systems containing a variety of polycyclic and heterocyclic rings.

Pd-catalyzed alkyl to aryl migration and cyclization: an efficient synthesis of fused polycycles via multiple C-H activation.

A novel palladium migration methodology for the synthesis of complex fused polycycles has been developed. This process involves 1,4-palladium alkyl to aryl migrations via through-space C-H activation, followed by intramolecular arylation or an intermolecular Heck reaction providing a very efficient way to synthesize fused ring systems.

1,4-palladium migration via C-H activation, followed by arylation: synthesis of fused polycycles.

A novel palladium migration/arylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that these palladium-catalyzed C-H activation reactions parallel electrophilic aromatic substitution.

Novel 1,4-palladium migration in organopalladium intermediates derived from o-iodobiaryls.

A novel 1,4-palladium migration in organopalladium intermediates derived from o-iodobiaryls has been observed under modified Heck reaction conditions. This migration process can be switched "on" or "off" by simply choosing the appropriate reaction conditions.

Synthesis of fluoren-9-ones by the palladium-catalyzed cyclocarbonylation of o-halobiaryls.

The synthesis of various substituted fluoren-9-ones has been accomplished by the palladium-catalyzed cyclocarbonylation of o-halobiaryls. The cyclocarbonylation of 4'-substituted 2-iodobiphenyls produces very high yields of 2-substituted fluoren-9-ones bearing either electron-donating or electron-withdrawing substituents. 3'-Substituted 2-iodobiphenyls afford 3-substituted fluoren-9-ones in excellent yields with good regioselectivity.