Products active on arthropod-IV Insect juvenile hormone mimics—4: hydrindane analogues of cecropia juvenile hormone

Synthesis of cis-hydrindane analogues (2,3) of Cecropia juvenile hormone-I from common intermediate cis-hydrindane-2, 5-dione is presented. The analogues are only moderately active against Dysdercus cingulatus.     

Extractive spectrophotometric determination of nitrite in polluted waters

Nitrite is diazotised with p-nitroaniline in hydrochloric acid and coupled with 8-quinolinol in alkaline medium to give a purple azo dye (λ_max = 550 nm, ? = 3.88 × 10⁴ l mol^-1 cm^-1). Extraction of the dye into 3-methyl-1-butanol shifts the absorption maximum to 570 nm and improves the apparent molar absorptivity to 5.852 × 10⁴ l mol^-1 cm^-1. Beer's law is obeyed for 0.01–0.06 ppm nitrite. The Sandell sensitivity is 0.00078 μg cm^-2. The method is applicable to polluted waters.     

Fly‐Ash‐Supported Synthesis of 2‐Mercaptobenzothiazole Derivatives under Microwave Irradiation

Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach.     

Aminomethyl Transfer (Mannich) Reactions Between an O-Triethylsilylated Hemiaminal and Anilines,RnC6H5−nNH2 Leading to New Diamines,Triamines, Imines,or 1,3,5-Triazines Dependent upon Substituent R

The reactions of the Mannich reagent Et₃SiOCH₂NMe₂ ( 1 ) with a variety of anilines (mono-substituted RC₆H₄NH₂, R=H, 4-CN, 4-NO₂, 4-Ph, 4-Me, 4-MeO, 4-Me₂N; di-substituted R₂C₆H₃NH₂, R₂=3,5-(CH₃)₂, 3,5-(CF₃)₂; tri-substituted R₃C₆H₂NH₂, R₃=3,5-Me₂-4-Br and a “super bulky” aniline (Ar*NH₂) [Ar*=2,6-bis(diphenylmethyl)-4-tert-butylphenyl]) led to the formation of a range of products dependent upon the substituent. With electron-withdrawing substituents, previously unknown diamines, RC₆H₄NH(CH₂NMe₂) [R=CN ( 2 a ), NO₂ ( 2 b )] and R₂C₆H₃NH(CH₂NMe₂) [R₂=3,5-(CF₃)₂ ( 2 c) ] were formed. Further reaction of 2 a , b , c with 1 yielded the corresponding triamines RC₆H₄N(CH₂NMe₂)₂ (R=CN ( 3 a ), NO₂ ( 3 b ) and R₂C₆H₃N(CH₂NMe₂)₂, R₂=3,5-(CF₃)₂ ( 3 c ). The new polyamines were characterized by NMR spectroscopy, and for 2 a , 2 c _, and 3 c , by single crystal XRD. In the case of electron-donating groups, R=4-OMe, 4-NMe₂, 4-Me, 3,5-Me₂, 3,5-Me₂-4-Br, and for R=4-Ph, the reactions with 1 immediately led to the formation of the related 1,3,5-triazines, R=4-MeO ( 5 a ), 4-Me₂N ( 5 b ), 4-Me ( 5 c ), 3,5-Me₂ ( 5 d ), 3,5-Me₂-4-Br ( 5 e ), 4-Ph ( 5 f ), 4-Cl ( 5 g ). The “super bulky” aniline rapidly produced a single product, namely the corresponding imine Ar*N=CH₂ ( 4 ) which was also characterized by single crystal XRD. Imine 4 is both thermally and oxidatively stable. All reactions are very fast, thus based upon the presence of Si we are tempted to denote the reactions of 1 as examples of “Silick” chemistry.     

Estimating Individual Treatment Effect in Observational Data Using Random Forest Methods

Estimation of individual treatment effect in observational data is complicated due to the challenges of confounding and selection bias. A useful inferential framework to address this is the counterfactual (potential outcomes) model, which takes the hypothetical stance of asking what if an individual had received both treatments. Making use of random forests (RF) within the counterfactual framework we estimate individual treatment effects by directly modeling the response. We find that accurate estimation of individual treatment effects is possible even in complex heterogenous settings but that the type of RF approach plays an important role in accuracy. Methods designed to be adaptive to confounding, when used in parallel with out-of-sample estimation, do best. One method found to be especially promising is counterfactual synthetic forests. We illustrate this new methodology by applying it to a large comparative effectiveness trial, Project Aware, to explore the role drug use plays in sexual risk. The analysis reveals important connections between risky behavior, drug usage, and sexual risk. Supplementary material for this article is available online.     

Plant Extract: A Promising Biomatrix for Ecofriendly,Controlled Synthesis of Silver Nanoparticles

Uses of plants extracts are found to be more advantageous over chemical, physical and microbial (bacterial, fungal, algal) methods for silver nanoparticles (AgNPs) synthesis. In phytonanosynthesis, biochemical diversity of plant extract, non-pathogenicity, low cost and flexibility in reaction parameters are accounted for high rate of AgNPs production with different shape, size and applications. At the same time, care has to be taken to select suitable phytofactory for AgNPs synthesis based on certain parameters such as easy availability, large-scale nanosynthesis potential and non-toxic nature of plant extract. This review focuses on synthesis of AgNPs with particular emphasis on biological synthesis using plant extracts. Some points have been given on selection of plant extract for AgNPs synthesis and case studies on AgNPs synthesis using different plant extracts. Reaction parameters contributing to higher yield of nanoparticles are presented here. Synthesis mechanisms and overview of present and future applications of plant-extract-synthesized AgNPs are also discussed here. Limitations associated with use of AgNPs are summarised in the present review.     

Novel Schiff bases–based thiophenes: Design,synthesis and biological evaluation

2-amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile derivatives have been synthesized from 1-(3-fluoro-4-methoxyphenyl)ethanone, malononitrile, mild base, and sulfur powder using the Gewald method through a multistep reaction sequence. The structures of newly synthesized compounds were established on the basis of their elemental analyses, IR, ¹H NMR, ¹³C NMR, and mass spectral data, and then synthesized compounds were screened for their in vitro antimicrobial activity. Among them, derivatives 3b (thiphene), 3f (pyrazole), and 3d (halogen) showed good activity and remaining derivatives exhibited moderate activity.     

Isolation and ring-opening of new 1-sila-3-metallacyclobutanes (eta 5-C5H4Fe)(CO)2CH2SiR2 leading to a new class of organometallic polymer

Treatment of FpCH2SiR2Cl [Fp = (eta5-C5H5)Fe(CO)2] with lithium diisopropylamide leads to the formation of new metallacycle complexes. When R2 = Me2 and MenBu, these ring-open to form a new class of organometallic polymer. When R2 = nBu2, the metallacycle resists ring-opening and may be structurally characterized as the Ph3P-substituted species.