A Convenient Diels-Alder Approach toward Potential Polyketide-like Antibiotics Using α-Activated α,ß-Unsaturated 4,4-Dimethyl-1-tetralones as Dienophiles.

Making use of a Diels-Alder approach based on various α,ß-unsaturated 2-carbomethoxy-4,4-dimethyl-1-tetralones as novel dienophiles, the corresponding polycyclic adducts could be efficiently synthesized in good to high yields (74~99%) in the presence of Lewis acid (e.g., SnCl4). Accordingly, a synthetically useful platform is established to provide a focused aromatic polyketide-like library for screening of potential natural and non-natural antimicrobial agents.

Development of Stem-Cell-Mobilizing Agents Targeting CXCR4 Receptor for Peripheral Blood Stem Cell Transplantation and Beyond.

The function of the CXCR4/CXCL12 axis accounts for many disease indications, including tissue/nerve regeneration, cancer metastasis, and inflammation. Blocking CXCR4 signaling with its antagonists may lead to moving out CXCR4+ cell types from bone marrow to peripheral circulation. We have discovered a novel series of pyrimidine-based CXCR4 antagonists, a representative (i.e., 16) of which was tolerated at a higher dose and showed better HSC-mobilizing ability at the maximal response dose relative to the approved drug 1 (AMD3100), and thus considered a potential drug candidate for PBSCT indication. Docking compound 16 into the X-ray crystal structure of CXCR4 receptor revealed that it adopted a spider-like conformation striding over both major and minor subpockets. This putative binding mode provides a new insight into CXCR4 receptor-ligand interactions for further structural modifications.

A Novel CXCR4 Antagonist CX549 Induces Neuroprotection in Stroke Brain.

C-X-C chemokine receptor type 4 (CXCR4) is a receptor for a pleiotropic chemokine CXCL12. Previous studies have shown that the acute administration of the CXCR4 antagonist AMD3100 reduced neuroinflammation in stroke brain and mobilized bone marrow hematopoietic stem cells (HSCs). The purpose of this study was to characterize the neuroprotective and neurotrophic effect of a novel CXCR4 antagonist CX549. We demonstrated that CX549 had a higher affinity for CXCR4 and was more potent than AMD3100 to inhibit CXCL12-mediated chemotaxis in culture. CX549 effectively reduced the activation of microglia and improved neuronal survival after injury in neuron/microglia cocultures. Early poststroke treatment with CX549 significantly improved behavioral function, reduced brain infarction, and suppressed the expression of inflammatory markers. Compared to AMD3100, CX549 has a higher affinity for CXCR4, is more efficient to mobilize HSCs for transplantation, and induces behavioral improvement. Our data support that CX549 is a potent anti-inflammatory agent, is neuroprotective against ischemic brain injury, and may have clinical implications for the treatment of stroke.

Synthesis of fully substituted dispirocyclohexanes by organocatalytic [2 + 2 + 2] annulation strategy between 2-arylideneindane-1,3-diones and aldehydes.

An interesting organocatalytic reaction between 2-arylideneindane-1,3-diones and aldehydes has been developed that gives fully substituted cyclohexanes that bear two all-carbon quaternary centers. The dispirocyclohexanes were obtained in reasonable-to-good chemical yields and with high stereoselectivities (>95:5 d.r. and up to 99% ee) using a catalytic amount of commercially available α,α-l-diphenylprolinol trimethylsilyl ether (5 mol %) and DABCO (20 mol %) in DMF at -20 °C. The reaction proceeds through a unique Michael/Michael/aldol reaction that requires 2 equiv of the 2-arylideneindane-1,3-dione.