Conformationally restrained carbazolone-containing α,γ-diketo acids as inhibitors of HIV integrase

A solvent controlled regioselective synthesis of 2- and 4-substituted α-carbolines under palladium catalysis

A facile method for the chemodivergent synthesis of α-carbolines 1via palladium catalyzed [3+3] annulations of tosyliminoindolines 6 with α, β-unsaturated aldehydes 7 is described. Mechanistically, this cascade reaction proceeds through either a carba-Michael (in DMF) or aza-Michael (in NMA) pathway followed by intramolecular cyclization of the intermediate. A preliminary photo-physical study on selected products is also reported.

Molecular imaging of NAD+ -dependent deacetylase SIRT1 in the brain

INTRODUCTION

Aging is an inevitable physiological process and the biggest risk factor of Alzheimer's disease (AD). Developing an imaging tracer to visualize aging-related changes in the brain may provide a useful biomarker in elucidating neuroanatomical mechanisms of AD.

METHODS

We developed and characterized a new tracer that can be used to visualize SIRT1 in brains related to aging and AD by positron emission tomography imaging.

RESULTS

The SIRT1 tracer displayed desirable brain uptake and selectivity, as well as stable metabolism and proper kinetics and distribution in rodent and nonhuman primate brains. This new tracer was further validated by visualizing SIRT1 in brains of AD transgenic mice, compared to nontransgenic animals.

DISCUSSION

Our SIRT1 tracer not only enables, for the first time, the demonstration of SIRT1 in animal brains, but also allows visualization and recapitulation of AD-related SIRT1 neuropathological changes in animal brains.

Diverse outcomes of CO2 fixation using alkali metal amides including formation of a heterobimetallic lithium-sodium carbamato-anhydride via lithium-sodium bis-hexamethyldisilazide

Fixation of CO2 by lithium amides derived from pyrrole and diisopropylamine generates a lithium carbamate polymer and dodecamer respectively. Moving to lithium-sodium hexamethyldisilazide produces a more complicated, intriguing reaction, where unusually the bimetallic composition is maintained in the product but its composition contains both carbamato and anhydride functionalities.

Rh(III)-Catalyzed C-H Activation/Intramolecular Cyclization: Access to N-Acyl-2,3-dihydro-1H-carbazol-4(9H)-ones from Cyclic 2-Diazo-1,3-diketones and N-Arylamides

A Rh(III)-catalyzed C-H activation/cyclization cascade reaction is described. The reaction involves cyclic 2-diazo-1,3-diketones and N-arylamides, and it proceeds via an intermolecular C-C bond formation and subsequent intramolecular C-N bond formation. A variety of N-acyl-2,3-dihydro-1H-carbazol-4(9H)-ones were obtained under mild conditions in good to excellent yields (65-90%). Key features of this strategy include high-efficiency, operational simplicity, scalability, and broad functional-group tolerance. In addition, H2O and N2 are the only byproducts. Carbazole derivatives with free NH groups can be easily obtained through N-deprotection reactions.

Conserved hydrogen bonding in tetrahydrocarbazolone derivatives: influence of solution-state assembly on crystal form nucleation

Two tetrahydocarbazolone derivatives were found to show multiple unsolvated crystal forms. A persistent dimer motif was detected in solution by FTIR spectroscopy that is maintained in the kinetic crystal forms. Rationally introduced steric bulk induces the formation of a more stable catemeric form.

Conformational restriction: an effective tactic in 'follow-on'-based drug discovery

The conformational restriction (rigidification) of a flexible ligand has often been a commonly used strategy in drug design, as it can minimize the entropic loss associated with the ligand adopting a preferred conformation for binding, which leads to enhanced potency for a given physiological target, improved selectivity for isoforms and reduced the possibility of drug metabolism. Therefore, the application of conformational restriction strategy is a core aspect of drug discovery and development that is widely practiced by medicinal chemists either deliberately or subliminally. The present review will highlight current representative examples and a brief overview on the rational design of conformationally restricted agents as well as discuss its advantages over the flexible counterparts.

3,9-Dimethyl-2,3-dihydro-spiro-[carb-az-ole-1,2'-[1,3]dithio-lan]-4(9H)-one

The title compound, C₁₆H₁₇NOS₂, consists of a carbazole skeleton with methyl and dithiol­ane groups as substituents. In the indole ring system, the benzene and pyrrole rings are nearly coplanar, forming a dihedral angle of 1.02 (11)°. The cyclo­hexenone ring has a twisted conformation, while the dithiol­ane ring adopts an envelope conformation with one of the CH₂ C atoms at the flap. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into supra­molecular chains nearly parallel to the c axis. These hydrogen bonds together with weak C—H⋯π inter­actions link the molecules into a three-dimensional supramolecular network.

Chiral indane skeleton based thiourea catalyzed highly stereoselective cascade Michael-enolation-cyclization reaction

An efficient asymmetric cascade reaction catalyzed by a chiral bifunctional indane amine-thiourea catalyst has been developed. From a broad substrate scope, chiral dihydro-2H-pyran complexes that contained two stereogenic centers were obtained in a one-pot manner in good to excellent yields (72-97%) and high to excellent stereoselectivities (92-97% ee).

HIV-1 Integrase Inhibitors: A Review of Their Chemical Development

Highly active antiretroviral therapy (HAART) significantly decreases plasma viral load, increases CD4+ T-cell counts in HIV-1-infected patients and has reduced progression to AIDS in developed countries. However, adverse side effects, and emergence of drug resistance, mean there is still a demand for new anti-HIV agents. The HIV integrase (IN) is a target that has been the focus of rational drug design over the past decade. In 2007, raltegravir was the first IN inhibitor approved by the US Food and Drug Administration for antiretroviral combination therapy, while another IN inhibitor, elvitegravir, is currently in Phase III clinical trials. This article reviews the development and resistance profiling of small molecule HIV-1 IN inhibitors.

A mild, catalytic and efficient Nazarov cyclization mediated by phosphomolybdic acid

A mild, selective and efficient Nazarov cyclization of divinyl ketones catalyzed by phosphomolybdic acid (PMA) is described. The process demonstrates a broad substrate scope with functional group tolerance under short reaction times. PMA supported on silica gel is more efficient than the bulk catalyst and is recycled up to three times without significant activity loss.

Integration of human immunodeficiency virus as a target for antiretroviral therapy

PURPOSE OF REVIEW

Most of the studies investigating inhibition of human immunodeficiency virus integration have focused on blocking the enzymatic functions of HIV integrase, with the predominant judgment that integration inhibitors need to block at least one of the integrase-catalyzed reactions. Recent studies, however, have highlighted the importance of other proteins and their contacts with integrase in the preintegration complex, and their involvement in chromosomal integration of the viral DNA.

RECENT FINDINGS

Promising results of clinical trials for two new integrase inhibitors were announced recently, providing the proof of the concept for using HIV-1 integrase inhibitors as antiretroviral therapy. Two strategies are currently employed for the development of novel inhibitors of HIV integrase: synthesis of hybrid molecules comprising core structures of two or more known inhibitors, and three-dimensional pharmacophore searches based on previously discovered compounds. By highlighting the role of the cellular cofactor LEDGF/p75 in HIV integration, novel approaches are indicated that aim to develop compounds altering contact between HIV integrase and integration cofactors.

SUMMARY

By the discovery of novel inhibitors and targets for HIV integration, coupled with recent studies in characterizing preintegration complex formation, new insight is provided for the rational design of anti-HIV integration inhibitors.

Synthesis and in-vitro antitumor activities of some mannich bases of 9-alkyl-1,2,3,4-tetrahydrocarbazole-1-ones

A novel series of 2-substituted aminomethyl-9-alkyl-1,2,3,4-tetrahydrocarbazole-1-ones 5a-q was synthesized via aminomethylation of 9-alkyl-1,2,3,4-tetrahydrocarbazole-1-ones 4a-e with hydrochlorides of the respective amines 6a-m. The structures of these newly synthesized compounds were characterized by (1)H-NMR, MS, and elemental analysis. All the compounds were tested for their cytotoxic activity in vitro against four human tumor cell lines including human non-small lung cancer cells (A549), human gastric adenocarcinoma (SGC), human colon cancer cell (HCT116), human myeoloid leukemia cells (K562), and one multi-drug resistant subline (KB-VCR). Most compounds showed moderate to potent cytotoxic activity against the tested cell lines. Preliminary mechanism research indicated that the most promising compound, 2-diethylaminomethyl-9-methyl-1,2,3,4-tetrahydrocarbazole-1-one 5c, exhibited a potential inhibitory effect against microtubule.

HIV-1 integrase inhibitors: 2005-2006 update

HIV-1 integrase (IN) catalyzes the integration of proviral DNA into the host genome, an essential step for viral replication. Inhibition of IN catalytic activity provides an attractive strategy for antiretroviral drug design. Currently two IN inhibitors, MK-0518 and GS-9137, are in advanced stages of human clinical trials. The IN inhibitors in clinical evaluation demonstrate excellent antiretroviral efficacy alone or in combination regimens as compared to previously used clinical antiretroviral agents in naive and treatment-experienced HIV-1 infected patients. However, the emergence of viral strains resistant to clinically studied IN inhibitors and the dynamic nature of the HIV-1 genome demand a continued effort toward the discovery of novel inhibitors to keep a therapeutic advantage over the virus. Continued efforts in the field have resulted in the discovery of compounds from diverse chemical classes. In this review, we provide a comprehensive report of all IN inhibitors discovered in the years 2005 and 2006.

Strategies for identification of HIV-1 integrase inhibitors

HIV-1 integrase, which catalyzes the joining of viral DNA to the host cell DNA, has attracted considerable attention as a target for the design and screening of novel anti-HIV drugs as it is essential for virus replication and the establishment of persistent infection. Progress in the identification of different classes of compounds that block integrase activity has been summarized recently in several excellent reviews. Here, we present a brief overview of integrase inhibition, highlighting some of the unusual properties of this protein and important considerations in searching for potential new inhibitors and their evaluation.