An account of the synthetic utility of masked o-benzoquinones is provided. The inter- and intramolecular Diels-Alder reactions of in situ generated masked o-benzoquinones produced cycloadducts in excellent selectivities. New synthetic methodologies have been developed for the synthesis of highly substituted ring systems including bicyclo[2.2.2]octenones, oxatricycles, triquinanes, polysubstituted cyclohexanes, and bicyclo[4.2.2]decenones with complete stereocontrol from easily accessible 2-methoxyphenols via the Diels-Alder reaction of masked o-benzoquinones. Other reactions of adducts derived from masked o-benzoquinones are also described. The efficacy of our methodology is demonstrated by several examples of the total synthesis of natural products.

HTS hit 7 was modified through hybrid design strategy to introduce a chiral side chain followed by introduction of Michael acceptor group to obtain potent EGFR kinase inhibitors 11 and 19. Both 11 and 19 showed over 3 orders of magnitude enhanced HCC827 antiproliferative activity compared to HTS hit 7 and also inhibited gefitinib-resistant double mutant (DM, T790M/L858R) EGFR kinase at nanomolar concentration. Moreover, treatment with 19 shrinked tumor in nude mice xenograft model.

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By using a cell-based high throughput screening campaign, a novel angelicin derivative 6a was identified to inhibit influenza A (H1N1) virus induced cytopathic effect in Madin-Darby canine kidney cell culture in low micromolar range. Detailed structure-activity relationship studies of 6a revealed that the angelicin scaffold is essential for activity in pharmacophore B, while meta-substituted phenyl/2-thiophene rings are optimal in pharmacophore A and C. The optimized lead 4-methyl-9-phenyl-8-(thiophene-2-carbonyl)-furo[2,3-h]chromen-2-one (8g, IC(50) = 70 nM) showed 64-fold enhanced activity compared to the high throughput screening (HTS) hit 6a. Also, 8g was found effective in case of influenza A (H3N2) and influenza B virus strains similar to approved anti-influenza drug zanamivir (4). Preliminary mechanistic studies suggest that these compounds act as anti-influenza agents by inhibiting ribonucleoprotein (RNP) complex associated activity and have the potential to be developed further, which could form the basis for developing additional defense against influenza pandemics.