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ChemInform Abstract: Synthesis of 5-Substituted 2,3-Dihydrobenzofurans in a One-Pot Oxidation/Cyclization Reaction.
2012
The oxidation of N-protected p-aminophenol derivatives to quinone imides is combined with cycloaddition towards azadiene (II) in a one-pot reaction to give dihydrobenzofuran derivatives in moderate to good yields.
Structural study of ethyl 3-arylcarbamoyl-2,3-diazabicyclo[2.2.1]hept-5-ene-2-carboxylates: conformation and transmission of substituent effects acro…
2001
Nine new ethyl 3-arylcarbamoyl-2,3-diazabicyclo[2.2.1]hept-5-ene-2-carboxylates were prepared by a [4 + 2] cycloaddition and their FTIR, 1H, 13C and 15N NMR spectra were measured and assigned. Single crystals were grown for five compounds and their X-ray data were obtained. The electronic structure and the conformations were calculated by the semi-empirical AM1 method. Using correlations between the spectral, empirical and theoretical structural data, the transmission of substituent effects and the preferential conformation connected with the consecutive double nitrogen inversion and regarding the mutual orientation of NH and CO bonds were investigated. The results are compared with those f…
Experimental and Theoretical Investigations of Structural Trends for Selenium(IV) Imides and Oxides: X-ray Structure of Se3(NAd) 2
2004
The thermal decomposition of Se(NAd)(2) (Ad = 1-adamantyl) in THF was monitored by (77)Se NMR and shown to give the novel cyclic selenium imide Se(3)(NAd)(2) as one of the products. An X-ray structural determination showed that Se(3)(NAd)(2) is a puckered five-membered ring with d(Se-Se) = 2.404(1) A and |d(Se-N)| = 1.873(4) A. On the basis of (77)Se NMR data, other decomposition products include the six-membered ring Se(3)(NAd)(3), and the four-membered rings AdNSe(micro-NAd)(2)SeO and OSe(micro-NAd)(2)SeO. The energies for the cyclodimerization of E(NR)(2) and RNEO (E = S, Se; R = H, Me, (t)Bu, SiMe(3)), and the cycloaddition reactions of RNSeO with E(NR)(2), RNSO(2) with Se(NR)(2), and S…
Synthesis and Stereochemistry of Diepoxynaphthacenes and Tetraepoxyheptacenes
1997
Cycloaddition reactions of 1,4-dihydro-1,4-epoxynaphthalenes (2) and benzo[c]furans (4), generated in situ from the tetracyclone adducts of 2, yield the diepoxynaphthacenes 5 (Schemes 1, 2). Out of 4 possible stereoisomers an exo-exo and an exo-endo geometry (A and C in Scheme 3) can be realized. The ratio A:C varies from pure A to pure C depending on the substituents of 2 and 4. Stereoisomeric heptacenes 7 can be obtained by a twofold cycloaddition of the same type (Scheme 4). Only one π bond of reactive alkynes such as cyclooctyne or acetylenedicarboxylate is capable of an addition to 4 (Schemes 5, 6).
Band-Shaped Structures by Repetitive Cycloaddition Reactions of Benzo[1,2-b:4,5-b′]bisthiete
1997
Benzo[1,2-b:4,5-b′]bisthiete (1) undergoes stepwise thermal opening of the 4-membered rings, thereby generating two highly reactive 8π systems (Scheme 1). In the presence of 1,4-dihydro-1,4-epoxynaphthalenes 2, the dithiaheptacene derivatives 3 are formed, dehydration of which leads to the compounds 4 and 5 (Scheme 2). Repetitive cycloaddition reactions of 1 with the twofold 2π component 11 (Scheme 3) yield the oligomers 15 with statistically bent (and possibly cyclic) structures (Schemes 4 and 5). While 15 and the related oligomers 14 are freely soluble in many organic solvents, the dehydrated systems 16 (Scheme 6) are totally insoluble.
A Validation Methodology for a Combined Heating Cooling and Power (CHCP) Pilot Plant
2004
A great number of variables significantly influence the energetic, environmental and economic results of CHP (Combined Heating and Power) and CHCP (Combined Heating Cooling and Power) plants operation, and as a consequence their project activity is rather complex. In order to select the best layout and properly size the machines, detailed data on hourly electric, thermal, and cooling demand are necessary, so that a series of plant life cycle simulations may have to be carried out. Unfortunately, such detailed data are rarely available, because energy consumptions data for existing buildings are usually derived from aggregated monthly or bimonthly gas and electricity bills. Even more difficu…
Characterization of cooling loads in the wine industry and novel seasonal indicator for reliable assessment of energy saving through retrofit of chil…
2020
Abstract The food sector is a major consumer of energy and growing efforts are being made in the search for solutions that will guarantee the efficient and sustainable use of energy resources. Among the different sectors, wineries are attracting particular interest due to the continuous growth of the global market and production. Surveys conducted in the winemaking sector have highlighted the importance of performing accurate energy audits and have identified the installation of efficient refrigeration systems as a promising solution in a variety of cases. Unfortunately, the savings achievable by efficient cooling technologies are often estimated using simplified approaches which do not tak…
Diversity-Oriented Synthesis of Highly Functionalized Alicycles across Dipolar Cycloaddition/Metathesis Reaction
2021
AbstractThis Account gives an insight into the selective functionalization of some readily available commercial cyclodienes across simple chemical transformations into functionalized small-molecular scaffolds. The syntheses involved selective cycloadditions, followed by ring-opening metathesis (ROM) of the resulting azetidin-2-one derivatives or isoxazoline frameworks and selective cross metathesis (CM) by discrimination of the C=C bonds on the alkenylated heterocycles. The CM protocols have been described when investigated under various conditions with the purpose on exploring chemodifferentiation of the olefin bonds and a study on the access of the corresponding functionalized β-lactam or…
L'effetto del sovraccarico di scelta: un'indagine su bambini, adolescenti, adulti e anziani
2021
L’effetto del sovraccarico di scelta è stato finora studiato prevalentemente su adulti. L’unico studio condotto su fasce di età diverse dagli adulti ha fornito una prima dimostrazione del fatto che le conseguenze negative dell’avere troppa scelta non si estendono in egual misura a bambini, adolescenti, adulti e anziani. Il presente lavoro si propone di indagare ulteriormente le conseguenze negative dell’avere troppa scelta su bambini, adolescenti e anziani. I dati suggeriscono che mentre gli adolescenti sono influenzati dal fenomeno in modo simile agli adulti, i bambini e gli anziani sembrano invece esserne immuni. Sono discusse le implicazioni teoriche e pratiche dei risultati e sono forni…
The Role of the Brand on Choice Overload
2019
Current research on choice overload has been mainly conducted with choice options not associated with specific brands. This study investigates whether the presence of brand names in the choice set affects the occurrence of choice overload. Across four studies, we find that when choosing among an overabundance of alternatives, participants express more positive feelings (i.e., higher satisfaction/confidence, lower regret and difficulty) when all the options of the choice set are associated with familiar brands, rather than unfamiliar brands or no brand at all. We also find that choice overload only appears in the absence of brand names, but disappears when all options contain brand names—eit…