Thermische Reaktionen mit 3-Phenyl-2H-azirinen; 1, 3-dipolare Cycloadditionen und En-Reaktionen

Benzonitrile p-nitrobenzylide ( 5 ) undergoes 1,3-dipolar cyclo-additions in the presence of 3-phenyl-2H-azirines ( 1 ), yielding in benzene at 0° 2-(p-nitrophenyl)-4,5-diphenyl-1,3-diazabicyclo[3.1.0]hex-3-enes ( 7 , scheme 2). Under the basic conditions of the reaction mixture, 7 a and 7 b are partially converted to 2-(p-nitrophenyl)-4,5-diphenyl-1,6-dihydropyrimidines ( 8a, b ) which are dehydrogenated by oxygen to the corresponding pyrimidines 9a and 9b , respectively. 3-Phenyl-2H-azirines ( 1 ) form, on heating at 145° in xylene in the presence of the azalactone 32 (2,4-diphenyl-Δ²-oxazolin-5-one), 4-(aziridin-2′-yl)-2,4-diphenyl-Δ²-oxazolin-5-ones ( 33 , scheme 11). 33 arises from an ene reaction of the enol form of 32 with 1 . Similar ene reactions are observed with the azirines 1 and dimedone ( 37 , scheme 12). Under the ene reaction conditions (xylene, 145°), the non-isolated intermediate primary adducts ( 38a and 38b ) undergo rearrangements of the vinylcyclopane-cyclopentene type to give 6,6-dimethyl-4-oxo-1,3-diphenyl-4, 5, 6, 7-tetrahydroisoindole ( 40 ) and 6, 6-dimethyl-4-oxo-3-phenyl-4, 5, 6, 7-tetrahedroindole ( 42 ), respectively.     

The preparation of 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides from the condensation‐cyclization of dilithiated β‐ketoesters with methyl 2‐(aminosulfonyl)benzoate or 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide

Several β‐ketoesters were dilithiated with an excess of lithium diisopropylamide, followed by condensation with methyl 2‐(aminosulfonyl)benzoate to give intermediates that were not isolated but cyclized to 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides. In most instances involving the ester‐sulfonamide, a single β‐ketoester tautomer is usually formed after recrystallization from ethanol. The same dilithiated β‐ketoesters generally condense less well with 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide (saccharin) under the same conditions to afford the same products usually in the same or lower yields. The use of N,N,N',N'‐tetramethylethylenediamine during these syntheses has sometimes resulted in improved yields of products.     

The preparation of 3‐substituted 1,2‐benzisothiazole 1,1‐dioxides from lithiated intermediates or grignard reagents and methyl 2‐(aminosulfonyl)benzoate

A polylithiated β‐ketoester, β‐diketone, or β‐ketoamide was condensed‐cyclized with lithiated methyl 2‐(aminosulfonyl)benzoate, to afford new 3‐substituted 1,2‐benzisothiazole 1,1‐dioxides. Some Grignard or organolithium reagents were also condensed‐cyclized with methyl 2‐(aminosulfonyl)benzoate to give 3‐substituted 1,2‐benzisothiazole 1,1‐dioxides.     

Metabolite Fingerprinting Using 1H-NMR Spectroscopy and Chemometrics for Classification of Three Curcuma Species from Different Origins

Curcuma longa, Curcuma xanthorrhiza, and Curcuma manga have been widely used for herbal or traditional medicine purposes. It was reported that turmeric plants provided several biological activities such as antioxidant, anti-inflammatory, hepatoprotector, cardioprotector, and anticancer activities. Authentication of the Curcuma species is important to ensure its authenticity and to avoid adulteration practices. Plants from different origins will have different metabolite compositions because metabolites are affected by soil nutrition, climate, temperature, and humidity. ¹H-NMR spectroscopy, principal component analysis (PCA), and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) were used for authentication of C. longa, C. xanthorrhiza, and C. manga from seven different origins in Indonesia. From the ¹H-NMR analysis it was obtained that 14 metabolites were responsible for generating classification model such as curcumin, demethoxycurcumin, alanine, methionine, threonine, lysine, alpha-glucose, beta-glucose, sucrose, alpha-fructose, beta-fructose, fumaric acid, tyrosine, and formate. Both PCA and OPLS-DA model demonstrated goodness of fit (R² value more than 0.8) and good predictivity (Q² value more than 0.45). All OPLS-DA models were validated by assessing the permutation test results with high value of original R² and Q². It can be concluded that metabolite fingerprinting using ¹H-NMR spectroscopy and chemometrics provide a powerful tool for authentication of herbal and medicinal plants.     

Preparation of 2‐(1‐phenyl‐1H‐pyrazol‐5‐yl)benzenesulfonamides from polylithiated C(α),N‐phenylhydrazones and methyl 2‐(aminosulfonyl)benzoate

Select C(α), N‐phenylhydrazones were dilithiated in excess lithium diisopropylamide followed by condensation with methyl 2‐(aminosulfonyl)benzoate and acid cyclization to afford new pyrazol‐benzenesul‐fonamides, 2‐(1‐phenyl‐1H‐pyrazol‐5‐yl)benzenesulfonamides.     

Recreational boating traffic: a chronic source of anthropogenic noise in the Wilmington, North Carolina Intracoastal Waterway

The majority of attention on the impact of anthropogenic noise on marine mammals has focused on low-frequency episodic activities. Persistent sources of mid-frequency noise pollution are less well studied. To address this data gap, the contribution of 25 physical, biological and anthropogenic factors to the ambient noise levels in the Wilmington, North Carolina Intracoastal Waterway were analyzed using a principal components analysis and least squares regression. The total number of recreational vessels passing through the waterway per hour is the factor that had the single greatest influence on environmental noise levels. During times of high boat traffic, anthropogenic noise is continuous rather than episodic, and occurs at frequencies that are biologically relevant to bottlenose dolphins. As a daily part of resident bottlenose dolphins' acoustic environment, recreational boating traffic may represent a chronic source of acoustic harassment.