A Copper-Mediated Conjugate Addition Approach to Analogues of Aconitine-Type Diterpenoid Alkaloids.

A copper-mediated conjugate addition of electron-rich aryl groups into a complex vinyl nitrile using arylmagnesium bromides is reported. The conjugate addition adducts were advanced toward the synthesis of designed aconitine-type analogues. The variation in oxygenation patterns on the arene coupling partner, introduced through the current conjugate addition approach, may ultimately provide insight into structure-activity relationships of the diterpenoid alkaloids.

A Unifying Synthesis Approach to the C-, C-, and C-Diterpenoid Alkaloids.

The secondary metabolites that comprise the diterpenoid alkaloids are categorized into C, C, and C families depending on the number of contiguous carbon atoms that constitute their central framework. Herein, we detail our efforts to prepare these molecules by chemical synthesis, including a photochemical approach, and ultimately a bioinspired strategy that has resulted in the development of a unifying synthesis of one C (weisaconitine D), one C (liljestrandinine), and three C (cochlearenine, paniculamine, and N-ethyl-1α-hydroxy-17-veratroyldictyzine) natural products from a common intermediate.

Slow O-demethylation of methyl triclosan to triclosan, which is rapidly glucuronidated and sulfonated in channel catfish liver and intestine.

The antibacterial personal care product triclosan is discharged in municipal waste, and converted in part by bacteria in sewage sludge and soil to its more lipid-soluble methyl ether, methyl triclosan. Triclosan and methyl triclosan have been detected in water, sediment, fish and invertebrates near sewage treatment facilities. Understanding the biotransformation of methyl triclosan and triclosan in a model food fish, the channel catfish, will be of value in assessing the likelihood that these compounds will bioaccumulate in exposed fish, and therefore potentially pass up the food chain.

Synthesis of the bridging framework of phragmalin-type limonoids.

An efficient synthesis of the octahydro-1H-2,4-methanoindene core of phragmalin-type limonoids, such as xyloccensins O and P, is reported. The success of the synthetic route is predicated on the use of network analysis in the retrosynthetic analysis and a Diels-Alder reaction for the synthesis of a key hydrindanone derivative.