Total synthesis of PDE-I and -II by copper-mediated double aryl amination

Structural Exploration of Novel Pyrethroid Esters and Amides for Repellent and Insecticidal Activity against Mosquitoes

The emergence of pyrethroid-resistant mosquitoes is a worldwide problem that necessitates further research into the development of new repellents and insecticides. This study explored the modification of existing pyrethroid acids to identify structural motifs that might not be affected by kdr active site mutations that elicit pyrethroid resistance. Because synthetic pyrethroids almost always contain activity-dependent chiral centers, we chose to focus our efforts on exploring alkoxy moieties of esters obtained with 1R-trans-permethrinic and related acids, which we showed in previous studies to have repellent and/or repellent synergistic properties. To this end, compounds were synthesized and screened for spatially acting repellency and insecticidal activity against the susceptible, Orlando, and pyrethroid-resistant, Puerto Rico, strains of Aedes aegypti mosquito. Screening utilized a high-throughput benchtop glass tube assay, and the compounds screened included a mixture of branched, unbranched, aliphatic, halogenated, cyclic, non-cyclic, and heteroatom-containing esters. Structure-activity relationships indicate that n-propyl, n-butyl, n-pentyl, cyclobutyl, and cyclopentyl substituents exhibited the most promising repellent activity with minimal kdr cross resistance. Preliminary testing showed that these small alcohol esters can be synergistic with phenyl amides and pyrethroid acids. Further derivatization of pyrethroid acids offer an interesting route to future active compounds, and while mosquitoes were the focus of this work, pyrethroid acids and esters have potential for use in reducing pest populations and damage in cropping systems as well.

[Synthetic Studies on Complex Natural Products Based on Development of a Novel Synthetic Method for Heteroaromatic Skeleton]

Among my recent work on the syntheses of complex natural products based on the development of a novel synthetic method for the heteroaromatic skeleton, this article primarily deals with the total syntheses of (+)-CC-1065, isobatzeline A/B, and batzeline A. These syntheses were accomplished via a novel indole synthesis utilizing a ring expansion reaction of benzocyclobutenone oxime sulfonate as the key step. The 1,2-dihydro-3H-pyrrolo[3,2-e]indole segments of (+)-CC-1065 were rapidly constructed via a two-directional double-ring expansion strategy. Highly substituted pyrrolidine-fused common 5-chloro-2-methylthioindoles of isobatzeline A/B and batzeline A were constructed using a ring expansion reaction of benzocyclobutenone oxime sulfonate with NaSMe and a benzyne-mediated cyclization/functionalization reaction.

Total Synthesis of (+)-CC-1065 Utilizing Ring Expansion Reaction of Benzocyclobutenone Oxime Sulfonate

An indole synthesis via ring expansion of benzocyclobutenone oxime sulfonate was developed. Utility of the indole synthesis was demonstrated by the total synthesis of (+)-CC-1065. The middle and right segments were constructed by a sequential ring expansion of the symmetrical benzo-bis-cyclobutenone. The left segment was also constructed via ring expansion of the methyl-substituted benzocyclobutenone oxime sulfonates. After condensation of these three segments, the dienone cyclopropane structure was formed to complete the total synthesis.

Fatty Acid and Related Potassium Kv2 Channel Blockers: Toxicity and Physiological Actions on Mosquitoes

Potassium channels constitute a very diverse group involved in neural signaling, neuronal activity, membrane potential maintenance, and action potential generation. Here, we tested the mammalian potassium channel blockers TRAM-34 and 5-hydroxydecanoate (5-HDC), as well as certain fatty acids (FA) that might fit in the lumen of the pore and block channel activity by obstructing K⁺ ion passage. Kv channel blockers could be leads for a novel pesticide type. Insecticidal activity was assessed by topical application to Anopheles gambiae adult mosquitoes, paralysis in a headless larval assay, at the cellular level with patch-clamp recordings of engineered HEK cells expressing AgKv2.1 channels, as well as central nervous system recordings from larval Drosophila melanogaster. With only one hydroxyl group difference, decanoic acid had a consistently greater effect than 5-HDC in blocking Kv channels, paralyzing larvae, and killing mosquitoes. The 11-dansylamino undecanoic acid (DAUDA) blockage of eukaryotic Kv channels is demonstrated for the first time, but it failed to kill adult mosquitoes. We synthesized alkyl esters from DAUDA and decanoic acid in an effort to improve cuticular penetration, but it had little impact upon adult toxicity. TRAM-34 and rolipram did not show activity on Kv channels nor potent insecticidal effect on adult mosquitoes. Furthermore, co-application of test compounds with permethrin did not increase mortality in adults. In conclusion, the compounds tested had modest insecticidal and synergistic activity.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

This review summarizes the isolation, structure determination, total syntheses and biological activities of simple indole alkaloids and those with a nonrearranged monoterpenoid unit, with literature coverage from 2012 to 2013.

Copper-mediated aromatic amination reaction and its application to the total synthesis of natural products

The historical background and recent update on copper-mediated aryl amination reactions including the recent C–H aryl amination and its application to the total syntheses of natural products are described.