Synthesis of 6‑Substituted 6<i>H</i>‑Indolo[2,3‑<i>b</i>]quinolines from Isoindigos

A facile approach to 6-aryl/alkyl substituted 6<i>H</i>-indolo­[2,3-<i>b</i>]­quinolines from mono-<i>N</i>-substituted isoindigo derivatives in the presence of SnCl₂·2H₂O in acid media is described. Pyrrole and pyridine rings are synchronously constructed in one pot for these tetracyclic molecules. A plausible reduction/hydrolysis/decarboxylation/cyclization/aromatization domino reaction mechanism is proposed. Bis-<i>N</i>-substituted isoindigo only gives the corresponding reduction product, 3,3′-bioxindole

Reduction of CuO into Cu with Guaiacol as a Model Compound of Lignin with a Homogeneous Catalyst of NaOH

The reduction of CuO with a lignin model compound, guaiacol, is investigated, to develop a new and green method for both Cu smelting and the utilization of lignin. The results showed that CuO can be completely reduced into Cu and guaiacol selectively converted to carboxylic acids such as fumaric, maleic, acetic, and formic acids at a mild temperature of 250 °C. The presence of NaOH has a significant effect on enhancing the reduction of CuO and the selective yield of carboxylic acids. Two possible reaction pathways were proposed for the reduction of CuO with guaiacol. One pathway involves the oxidative decomposition of guaiacol into carboxylic acids. The other reaction pathway proceeds with the polymerization of guaiacol into oligomers, which can be reused for CuO reduction due to their easy hydrolyzation to monomers under hydrothermal conditions

Stereoselective Synthesis of 2,8-Dioxabicyclo[3.3.1]nonane Derivatives via a Sequential Michael Addition/Bicyclization Reaction

A highly efficient and stereoselective synthesis of coumarin-, 1,3-cyclohexanedione-, and 1,4-naphthoquinone-fused 2,8-dioxabicyclo[3.3.1]­nonanes is described. This was achieved via a sequential Michael addition/bicyclization reaction from easily accessible 3-(2-hydroxyphenyl)-1-phenylprop-2-en-1-one derivatives. Three chemical bonds (one C–C bond and two C–O bonds), two six-membered cycles, and two stereogenic centers were formed in a one-pot operation

Area and aboveground biomass characteristics for five forest types in China during 2001–2013.

<p>DNF = deciduous needle leaf forests, ENF = evergreen needle leaf forests, MF = needle leaf and broadleaf mixed forests, DBF = deciduous broadleaf forests, EBF = evergreen broadleaf forests.</p><p>Area and aboveground biomass characteristics for five forest types in China during 2001–2013.</p

The diurnal variations of Q₁₀ estimated based on the seasonal variation in R_S at different time during one day.

<p>Values not given a common letter are significantly different from each other at P = 0.05. Bars represent the standard error.</p

Stereoselective Synthesis of 2,8-Dioxabicyclo[3.3.1]nonane Derivatives via a Sequential Michael Addition/Bicyclization Reaction

A highly efficient and stereoselective synthesis of coumarin-, 1,3-cyclohexanedione-, and 1,4-naphthoquinone-fused 2,8-dioxabicyclo[3.3.1]­nonanes is described. This was achieved via a sequential Michael addition/bicyclization reaction from easily accessible 3-(2-hydroxyphenyl)-1-phenylprop-2-en-1-one derivatives. Three chemical bonds (one C–C bond and two C–O bonds), two six-membered cycles, and two stereogenic centers were formed in a one-pot operation

Forest types and the distribution of AGBD data in China.

<p>The forest types are according to the 1:4000000 vegetation map of China. DNF = deciduous needle leaf forests, ENF = evergreen needle leaf forests, MF = needle leaf and broadleaf mixed forests, DBF = deciduous broadleaf forests, EBF = evergreen broadleaf forests. The AGBD data is from Luo <i>et al</i>. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130143#pone.0130143.ref018" target="_blank">18</a>].</p

Diurnal changes in (A) stem respiration per unit surface area (RS), (B) air relative humidity, (C) stem temperature and (D) air temperature.

<p>For each 3-hourly interval, measurements were averaged for the six sample trees in the whole growing season (May to Sep) from 2010 to 2012. The resulting standard errors are represented by the bars.</p

Location of study site in Saihanba National Forest Park, Hebei Province, China.

<p>Location of study site in Saihanba National Forest Park, Hebei Province, China.</p

Explanatory variables used in MTE.

<p>¹ The 2001–2013 summer values of MODIS reflectance and Vegetation Indices are calculated by averaging values from June to August during 2001–2013.</p><p>Explanatory variables used in MTE.</p