Heterocyclic privileged medicinal scaffolds involving pyridine, 1,4-dihydropyridine, chromeno[2,3-b]pyridine, and dihydro-1,4-dithiepine frameworks are prepared via a single-step multicomponent reaction of structurally diverse aldehydes with various thiols and malononitrile. Mechanistic studies of the synthetic pathway leading to pyridines reveal that 1,4-dihydropyridines undergo oxidation by the intermediate Knoevenagel adducts rather than by air oxygen. The use of o,o'-disubstituted aromatic aldehydes leads to the corresponding 1,4-dihydropyridines, whereas salicylic aldehydes result in chromeno[2,3-b]pyridines. Reactions of ethanedithiol as a thiol component produce dimeric pyridines with sterically unencumbered aldehydes, while o,o'-disubstituted aromatic aldehydes give dihydro-1,4-dithiepines. Thus, depending on the aldehyde and thiol types, diverse libraries of medicinally relevant compounds can be prepared by a simple one-step process involving no chromatography.

F]DFA to show that ribose preferentially accumulates in the liver, suggesting a striking tissue specificity for ribose metabolism. We demonstrate that solute carrier family 2, member 2 (also known as GLUT2), a glucose transporter expressed in the liver, is one ribose transporter, but we do not know if others exist. [ 18 F]DFA accumulation is attenuated in several mouse models of metabolic syndrome, suggesting an association between ribose salvage and glucose and lipid metabolism. These results describe a tool for studying ribose salvage and suggest that plasma ribose is preferentially metabolized in the liver. molecular imaging | sugar metabolism | Slc2a2

Pyrano[3,2-c]pyridone and pyrano[3,2-c]quinolone structural motifs are commonly found in alkaloids manifesting diverse biological activities. As part of a program aimed at structural simplification of bioactive natural products utilizing multicomponent synthetic processes, we developed compound libraries based on these privileged heterocyclic scaffolds. The selected library members display low nanomolar antiproliferative activity and induce apoptosis in human cancer cell lines. Mechanistic studies reveal that these compounds induce cell cycle arrest in the G2/M phase and block in vitro tubulin polymerization. Because of the successful clinical use of microtubule-targeting agents, these heterocyclic libraries are expected to provide promising new leads in anticancer drug design.