desickling action of urea is a concentration-dependent event. McCurdy and Mahmood (5) were successful in 14 trials out of 24 with i. v. urea, even though they also used urea at blood levels below those specified. Furthermore, they suggested that their failures might be dose-related. I am surprised that they did so well for the i. v. modality, since they used urea only at 70 to 120 mg/100 ml ins...

Asymmetric coupling proceeds efficiently between propargylic acetates, cycloalkenes and electron-rich heteroarenes including indoles, pyrroles, activated furans thiophenes. 2,3-Disubstituted tetrahydrofurans pyrrolidines are produced in trans configuration excellent enantiomeric ratios. The reaction via Wacker-type attack of nucleophilic on alkenes by allenyl PdII species.

ed by the ether oxygen of oxanorbornene and dehydration can occur along the pathway illustrated in Figure 7.10. Figure 7.10 Proton transfer from adsorbed DMF to the cycloadduct. At the same time, proton transfer of the acidic H of the adsorbed DMF complex to p-xylene is neither energetically favorable (∆G = +27.6 kcal/mol) and has a significant energy barrier (Ea = +26.6 kcal/mol). Once the pro...

The catalytic fast pyrolysis (CFP) of bio-derived furans offers a promising approach for sustainable aromatic production. ZSM-5 modified by different metal species (Zn, Mo, Fe, and Ga) was employed in the CFP enhancing effects species, loadings, weight hourly space velocity (WHSV) on product distributions from 2-methylfuran (MF) were systemically investigated. It is found that introduction Zn, ...

An efficient synthesis of tetrasubstituted furans was achieved from the corresponding α,β-unsaturated ketone derivatives, acid chlorides, and Bu3P in the presence of Et3N via a chemoselective intramolecular Wittig reaction as the key step. The presence of an additional electron-withdrawing group in the α-position of Michael acceptors controlled the chemoselectivities of presumable phosphorus yl...

Conditions allowing the one pot 2,5-diheteroarylation of 2,5-dibromothiophene derivatives in the presence of palladium catalysts are reported. Using KOAc as the base, DMA as the solvent and only 0.5-2 mol % palladium catalysts, the target 2,5-diheteroarylated thiophenes were obtained in moderate to good yields and with a wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrrol...

In cellulosic ethanol production, pretreatment of a biomass to facilitate enzymatic hydrolysis inevitably yields fermentation inhibitors such as organic acids, furans, and phenols. With representative inhibitors included in the medium at various concentrations, individually or in various combinations, ethanol production by Corynebacterium glutamicum R under growth-arrested conditions was invest...

An efficient and broadly applicable process is reported for the direct alkylation of C-H bonds in heteroarenes, privileged scaffolds in many areas of science. This reaction is based on the copper-catalyzed addition of alkyl radicals generated from activated secondary and tertiary alkyl bromides to a wide range of arenes, including furans, thiophenes, pyrroles, and their benzo-fused derivatives,...