Abiotic synthesis of amino acids and self-crystallization under prebiotic conditions.

Building on previous research on the origin and homochirality of life, this study focuses on analyses profiling important building blocks of life: the natural amino acids. The spark discharge variation of the iconic Miller experiment was performed with a reducing gas mixture of ammonia, methane, water and hydrogen. Amino acid analysis using liquid chromatography coupled with tandem mass spectrometry after pre-column derivatizaiton revealed the generation of several amino acids including those essential for life.

Catalytic asymmetric aziridination of α,β-unsaturated aldehydes.

The development, scope, and application of the highly enantioselective organocatalytic aziridination of α,β-unsaturated aldehydes is presented. The aminocatalytic azirdination of α,β-unsaturated aldehydes enables the asymmetric formation of β-formyl aziridines with up to >19:1 d.r.

Heterogeneous "Organoclick" Derivatization of Polysaccharides: Photochemical Thiol-ene Click Modification of Solid Cellulose.

A simple and direct method for derivatization of solid polysaccharides is presented. The novel methodology is based on the combination of organic acid-catalyzed esterification or etherification and photochemical thiol-ene click derivatization of a heterogeneous polysaccharide. The solid cellulose was "organoclick" modified with aryl, alkyl and polyester groups, respectively.

Dynamic kinetic asymmetric transformation (DYKAT) by combined amine- and transition-metal-catalyzed enantioselective cycloisomerization.

The first examples of one-pot highly chemo- and enantioselective dynamic kinetic asymmetric transformations (DYKATs) involving alpha,beta-unsaturated aldehydes and propargylated carbon acids are presented. These DYKATs, which proceed by a combination of catalytic iminium activation, enamine activation, and Pd(0)-catalyzed enyne cycloisomerization, give access to functionalized cyclopentenes with up to 99 % ee and can be used for the generation of all-carbon quaternary stereocenters.

[Ecological benefit evaluation of urban forests in Shenyang City based on QuickBird image and CITYgreen model].

Based on the urban forest coverage data interpreted from QuickBird image (2006) and the CITYgreen model, the benefits of Shenyang urban forest types with different canopy closure in carbon fixation and pollutant removal were investigated by means of sampling strategy. The results showed that the total amount of carbon storage, annual carbon sequestration, annual air pollutant removal, and their corresponding values were 0.51 Tg, 6858.

Genome-wide characterization of long terminal repeat -retrotransposons in apple reveals the differences in heterogeneity and copy number between Ty1-copia and Ty3-gypsy retrotransposons.

The conserved domains of reverse transcriptase (RT) genes of Ty1-copia and Ty3-gypsy groups of long terminal repeat (LTR) retrotransposons were isolated from the Malus domestica genome using degenerate oligonucleotide primers. Sequence analysis showed that 45% of Ty1-copia and 63% of Ty3-gypsy RT sequences contained premature stop codons and/or indels disrupting the reading frame. High heterogeneity among RT sequences of both Ty1-copia and Ty3-gypsy group retrotransposons was observed, but Ty3-gypsy group retrotransposons in the apple genome are less heterogeneous than Ty1-copia elements.

One-pot catalytic enantioselective domino nitro-michael/michael synthesis of cyclopentanes with four stereocenters.

A highly enantioselective organocatalytic one-pot synthesis of nitro-, formyl-, and ester-functionalized cyclopentanes with four stereocenters is presented. The cyclopentanes were formed as a predominant diasteroisomer and isolated in high yields with 97-99 % ee.

[Simulation of three-dimensional green biomass of urban forests in Shenyang City and the factors affecting the biomass].

Based on the fractal theory of forest growth, stepwise regression was employed to pursue a convenient and efficient method of measuring the three-dimensional green biomass (TGB) of urban forests in small area. A total of thirteen simulation equations of TGB of urban forests in Shenyang City were derived, with the factors affecting the TGB analyzed. The results showed that the coefficients of determination (R2) of the 13 simulation equations ranged from 0.

One-pot organocatalytic domino Michael/alpha-alkylation reactions: direct catalytic enantioselective cyclopropanation and cyclopentanation reactions.

The development of one-pot organocatalytic domino Michael/alpha-alkylation reactions between bromomalonates or bromoacetoacetate esters and alpha,beta-unsaturated aldehydes is presented. The chiral-amine-catalyzed reactions with bromomalonates as substrates give access to the corresponding 2-formylcyclopropane derivatives in high yields with excellent diastereoselectivity and up to 99 % ee. The catalytic domino Michael/alpha-alkylation reactions between 4-bromo-acetoacetate and enals provide a route for the synthesis of functionalized cyclopentanones in good to high yields with 93-99 % ee.

One-pot catalytic asymmetric cascade synthesis of cycloheptane derivatives.

A regiospecific, highly chemo-, diastereo-, and enantioselective one-pot catalytic cascade synthesis of cycloheptane derivatives is presented. In this chiral-amine-catalyzed asymmetric process, six new bonds and five new stereocenters were formed with excellent stereocontrol (>25:1 d.r.

[Estimation of Shenyang urban forest green biomass].

Based on ARC/GIS and by using the method of "planar biomass estimation", the green biomass (GB) of Shenyang urban forests was measured. The results demonstrated that the GB per unit area was the highest (3.86 m2.

Organocatalytic enantioselective conjugate addition of aldehydes to maleimides.

The highly enantioselective direct organocatalytic conjugate addition of aldehydes to maleimides is presented.

Organocatalytic asymmetric 5-hydroxyisoxazolidine synthesis: a highly enantioselective route to beta-amino acids.

The highly chemo- and enantioselective organocatalytic tandem reaction between N-protected hydroxyl amines and alpha,beta-unsaturated aldehydes is presented; the reaction provides access to 5-hydroxyisoxazolidines and beta-amino acids in high yields and with 90-99% ee.

A facile synthetic route to 2 H-chromenes: reconsideration of the mechanism of the DBU-catalyzed reaction between salicylic aldehydes and ethyl 2-methylbuta-2,3-dienoate.

Reactions of salicylaldehydes with ethyl buta-2,3-dienoate or penta-3,4-dien-2-one catalyzed by a catalytic amount of potassium carbonate produce the corresponding 2 H-chromene products in moderate to good yields under mild conditions. A plausible reaction mechanism is discussed in the light of the results of an 18O-labeling experiment. In addition, in view of these findings, the catalytic function of DBU in reactions of this kind is reconsidered.

Direct catalytic enantioselective alpha-aminomethylation of aldehydes.

The direct catalytic asymmetric alpha-aminomethylation of aldehydes is presented. The chiral amine and amino acid catalyzed reactions between unmodified aldehydes and a formaldehyde-derived imine precursor were fast and proceeded with high chemo- and enantioselectivities. The corresponding dibenzyl-protected gamma-amino alcohols were isolated in high yields with up to 98% ee after in situ reduction.

Catalytic enantioselective domino oxa-michael/aldol condensations: asymmetric synthesis of benzopyran derivatives.

The first direct organocatalytic asymmetric domino oxa-Michael/aldol condensation reaction is presented. The unprecedentedly simple, chiral, pyrrolidine-catalyzed asymmetric domino reactions between salicylic aldehyde derivatives and alpha,beta-unsaturated aldehydes proceed with high chemo- and enantioselectivities to give the corresponding chromene-3-carbaldehyde derivatives in high yields and with ee values of 83-98%.