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The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, Wisconsin, and the most western point of Lake Superior (46.74°, − 92.13°), has a long history of human development since Euro-American settlement ~ 200 years ago. Due to degradation from logging, hydrologic modification, industrial practices, and untreated sewage, the SLRE was designated an Area of Concern in 1987. Action has been taken to restore water quality including the installation of the Western Lake Superior Sanitary District in 1978 to help remove beneficial use impairments. A better understanding of historical impacts and remediation is necessary to help document progress and knowledge gaps related to water quality, so a paleolimnological study of the SLRE was initiated. Various paleolimnological indicators (pigments, diatom communities, and diatom-inferred phosphorus) were analyzed from six cores taken throughout the SLRE and another from western Lake Superior. Reductions in eutrophic diatom taxa such as Cyclotella meneghiniana and Stephanodiscus after 1970 in certain cores suggest an improvement in water quality over the last 40 years. However, in cores taken from estuarine bay environments, persistence of eutrophic taxa such as Cyclostephanos dubius and Stephanodiscus binderanus indicate ongoing nutrient problems. Sedimentary pigments also indicate cyanobacteria increases in bays over the last two decades. Diatom model-inferred phosphorus and contemporary monitoring data suggest some of the problems associated with excess nutrient loads have been remediated, but modern conditions (internal phosphorus loading, changing climate) may be contributing to ongoing water quality impairments in some locations. The integrated record of biological, chemical, and physical indicators preserved in the sediments will aid state and federal agencies in determining where to target their resources.

Triterpenoids have multiple biological properties, although little information is available regarding their toxicity. The present study evaluates the toxicity of two new synthetic lupane derivatives using distinct biological models including synthetic lipids membranes, isolated liver and heart mitochondria fractions, and cell lines in culture. The two novel triterpenoids caused perturbations in the organization of synthetic lipid bilayers, leading to changes in membrane fluidity. Inhibition of cell proliferation and mitochondrial and nuclear morphological alterations were also identified. Inhibition of mitochondrial oxygen consumption, transmembrane electric potential depolarization and induction of the mitochondrial permeability transition pore was observed, although effects on isolated mitochondrial fractions were tissue-dependent (e.g. liver vs. heart). The size and length of hydrocarbon chains in the two molecules appear to be determinant for the degree of interaction with mitochondria, especially in the whole cell environment, where more barriers for diffusion exist. The results suggest that the positively charged triterpenoids target mitochondria and disrupt bioenergetics.

1,1-Dihydro-1-tolylsulfonyl polyfluoroalkan-2-ones react with phthalimidosulfenyl chloride to form sulfenylated products on the active methylene group, 1-phthalimidothio-1-tolylsulfonyl polyfluoroalkan-2-ones. Decomposition of the latter leads to formation of 1-thioxo-1-tolylsulfonyl polyfluoroalkan-2-ones. These compounds undergo easily the hetero Diels–Alder reaction with electron-rich 1,3-dienes as dienophiles to give polyfluoroalkanoyl substituted derivatives of 5,6-dihydro-2H-thiins. 6-Arylsulfonyl-6-polyfluoroalkanoyl-5,6-dihydro-2H-thiins obtained react with alkali to give 5,6-dihydro-6-p-tolylsulfonyl-2H-thiins and with methanol to give 2-polyfluoroalkanoyl-6H-thiins.

1-Benzylsulfonyl-1,1-dihydropolyfluoroalkan-2-ones react with phthalimidosulfenyl chloride or succinimidosulfenyl chloride to form the sulfenylated products on the active methylene group, 1-benzylsulfonyl-1-phthalimido(succinimido)thiopolyfluoroalkan-2-ones. Decomposition of the latter leads to formation of 1-benzylsulfonyl-1-thioxopolyfluoroalkan-2-ones. These compounds easily undergo the hetero Diels–Alder reaction with electron-rich 1,3-dienes as dienophiles and with electron-rich olefins as hetero-1,3-dienes. Polyfluoroalkyl substituted derivatives of six-membered sulfur-containing heterocycles, 5,6-dihydro-2H-thiins and 2,3-dihydro-1,4-oxathiins, are obtained as a result of these reactions.

Polyfluorinated aliphatic aldehydes react with 1-phenyl-3-methylpyrazole-5-one, 1-phenyl-3-methyl-5-amino (N,N-dimethylaminomethylenamino)pyrazole and 1-phenyl-3-aminopyrazole-5-one at room temperature in the absence of catalyst with formation of 4-(1-hydroxypolyfluoroalkyl)pyrazoles. Dehydration of 4-(1-hydroxypolyfluoroalkyl)pyrazoles with morpholinosulfur trifluoride generates 4-polyfluoroalkylidenepyrazoles, which are active dienophiles and react with 2,3-dimethylbutadiene and cyclopentadiene forming spirocyclic pyrazole derivatives.

An excess of elemental iodine in N,N-dimethylacetamide enables effective 3/iodanylium-de-hydronation of terminal alkenes with 3-iodopropene derivatives and hydrogen iodide formation within minutes at room temperature. The optimal molar ratio of iodine to substrate was decreased to 1 : 1 when hydrogen iodide formed was oxidized on a platinum anode. The electrolytic oxidation recovers iodine as a reagent and diminishes the hydrogen iodide inhibitory action to accomplish the monoiodination. The proposed reaction mechanism is based on kinetic measurements and quantum mechanics calculations.

Triterpene derivatives were analyzed for anti-HIV-1 activity and for cellular toxicity. Betulinic aldehyde, betulinic nitrile, and morolic acid derivatives were identified to have anti-HIV-1 activity. These derivatives inhibit a late step in virus replication, likely virus maturation.

Polyfluorinated aliphatic aldehydes react with 1-phenyl-3-methylpyrazole-5-one, 1-phenyl-3-methyl-5-amino (N,N-dimethylaminomethylenamino)pyrazole and 1-phenyl-3-aminopyrazole-5-one at room temperature in the absence of catalyst with formation of 4-(1-hydroxypolyfluoroalkyl)pyrazoles. Dehydration of 4-(1-hydroxypolyfluoroalkyl)pyrazoles with morpholinosulfur trifluoride generates 4-polyfluoroalkylidenepyrazoles, which are active dienophiles and react with 2,3-dimethylbutadiene and cyclopentadiene forming spirocyclic pyrazole derivatives.

1-Benzylsulfonyl-1,1-dihydropolyfluoroalkan-2-ones react with phthalimidosulfenyl chloride or succinimidosulfenyl chloride to form the sulfenylated products on the active methylene group, 1-benzylsulfonyl-1-phthalimido(succinimido)thiopolyfluoroalkan-2-ones. Decomposition of the latter leads to formation of 1-benzylsulfonyl-1-thioxopolyfluoroalkan-2-ones. These compounds easily undergo the hetero Diels–Alder reaction with electron-rich 1,3-dienes as dienophiles and with electron-rich olefins as hetero-1,3-dienes. Polyfluoroalkyl substituted derivatives of six-membered sulfur-containing heterocycles, 5,6-dihydro-2H-thiins and 2,3-dihydro-1,4-oxathiins, are obtained as a result of these reactions.

A two-step preparation of 2,3-trans disubstituted tetrahydrofuran derivatives is reported from S-alkyl dithiocarbonates. The study of the group transfer reaction from xanthates and alkenes afforded intermediate S-alkyl dithiocarbonates. From 2,3-dihydrofuran derivatives, the displacement of the resulting anomeric xanthates with various nucleophiles in the presence of Lewis acid allowed the formation of new carbon-carbon and carbon-heteroatom bonds. This strategy was illustrated by a two-step synthesis of a precursor of modified 2'-beta-C-branched nucleoside analogues.

The A-ring oxidation/contraction of 3-oxotriterpenoids was developed as a two-step and “one pot” process. A benzylic acid type rearrangement of triterpenoid diosphenols gives (S)- as major and (R)-α-hydroxycarboxylic acids as minor reaction products. The absolute configurations were determined from the X-ray crystal structure analysis. The mechanism of ring contraction was modelled computationally at the DFT and MP2 levels of theory. The tautomeric triterpenoid A-seco δ-oxocarboxylic acids and A-ring hydroxy lactones formed after deep oxidation/acidification of 3-oxotriterpenoids.