Temperature-Controlled Divergent Asymmetric Synthesis of Indole-Based Medium-Sized Heterocycles through Palladium Catalysis

The divergent construction of chiral medium-sized rings is an essential but challenging task in organic synthesis. Herein, we report a temperature-controlled catalytic system for the divergent, enantioselective synthesis of different types of medium-sized rings starting from the same substrate set. Enabled by a planar chiral bisphosphine ligand, the palladium-catalyzed (5 + 4) and formal (5 + 2) annulations of cyclic aza-dienes and vinylethylene carbonates proceeded smoothly to afford a broad spectrum of indole-based medium-sized heterocycles in excellent yields with outstanding enantioselectivities. Those products could be further diversified through various functional group transformations. Moreover, mechanistic studies, including control experiments and DFT calculations, shed light on understanding the observed regio- and enantioselectivities of palladium-catalyzed (5 + n) cyclization

Temperature-Controlled Divergent Asymmetric Synthesis of Indole-Based Medium-Sized Heterocycles through Palladium Catalysis

The divergent construction of chiral medium-sized rings is an essential but challenging task in organic synthesis. Herein, we report a temperature-controlled catalytic system for the divergent, enantioselective synthesis of different types of medium-sized rings starting from the same substrate set. Enabled by a planar chiral bisphosphine ligand, the palladium-catalyzed (5 + 4) and formal (5 + 2) annulations of cyclic aza-dienes and vinylethylene carbonates proceeded smoothly to afford a broad spectrum of indole-based medium-sized heterocycles in excellent yields with outstanding enantioselectivities. Those products could be further diversified through various functional group transformations. Moreover, mechanistic studies, including control experiments and DFT calculations, shed light on understanding the observed regio- and enantioselectivities of palladium-catalyzed (5 + n) cyclization

Temperature-Controlled Divergent Asymmetric Synthesis of Indole-Based Medium-Sized Heterocycles through Palladium Catalysis

The divergent construction of chiral medium-sized rings is an essential but challenging task in organic synthesis. Herein, we report a temperature-controlled catalytic system for the divergent, enantioselective synthesis of different types of medium-sized rings starting from the same substrate set. Enabled by a planar chiral bisphosphine ligand, the palladium-catalyzed (5 + 4) and formal (5 + 2) annulations of cyclic aza-dienes and vinylethylene carbonates proceeded smoothly to afford a broad spectrum of indole-based medium-sized heterocycles in excellent yields with outstanding enantioselectivities. Those products could be further diversified through various functional group transformations. Moreover, mechanistic studies, including control experiments and DFT calculations, shed light on understanding the observed regio- and enantioselectivities of palladium-catalyzed (5 + n) cyclization

Temperature-Controlled Divergent Asymmetric Synthesis of Indole-Based Medium-Sized Heterocycles through Palladium Catalysis

The divergent construction of chiral medium-sized rings is an essential but challenging task in organic synthesis. Herein, we report a temperature-controlled catalytic system for the divergent, enantioselective synthesis of different types of medium-sized rings starting from the same substrate set. Enabled by a planar chiral bisphosphine ligand, the palladium-catalyzed (5 + 4) and formal (5 + 2) annulations of cyclic aza-dienes and vinylethylene carbonates proceeded smoothly to afford a broad spectrum of indole-based medium-sized heterocycles in excellent yields with outstanding enantioselectivities. Those products could be further diversified through various functional group transformations. Moreover, mechanistic studies, including control experiments and DFT calculations, shed light on understanding the observed regio- and enantioselectivities of palladium-catalyzed (5 + n) cyclization

Impoundment-induced nitrogen–phosphorus imbalance in cascade reservoirs alleviated by input of anthropogenic nutrients

<p>The ratio of nitrogen to phosphorus (N:P) is an important variable that has a close relationship with the ecological problems of nuisance algal blooms and eutrophication in aquatic environments in terms of nutrient limitation. Reservoirs generally have much higher retention efficiency for P than for N. This inherent dissimilarity in the N and P biogeochemical cycles likely results in N–P stoichiometric imbalance in downstream rivers and reservoirs, consequently causing an increase in the N:P ratio and aggravating P limitation. Here we determined the total N (TN) and total P (TP) concentrations in the cascade reservoirs of the Wujiang River and Lancangjiang River basins. The results show that TN:TP ratios in these 2 basins exhibited a common inverted V-shaped (∧) pattern downstream. We found that P is not only retained by reservoirs more efficiently than N but is also replenished at faster rates than N given anthropogenic impacts; consequently, the N–P imbalance caused by these impoundments is alleviated within a short distance downstream because of inputs of anthropogenic nutrients. Our research suggests that construction of cascade reservoirs does not necessarily lead to strict P deficiency and anomalously high N:P ratios downstream.</p

Analysis of variance of three factors (years, sites and treatments).

<p>Analysis of variance of three factors (years, sites and treatments).</p

Effect of five SN101 biocontrol agents on mortality of second-stage juveniles of <i>Heterodera glycines</i>.

<p>Effect of five SN101 biocontrol agents on mortality of second-stage juveniles of <i>Heterodera glycines</i>.</p

Effects of SN101 seed coating on soybean height and root length under greenhouse condition.

<p>Plants were treated with biocontrol seed coating-sn101, chemical seed coating-BFA and uncoated-CK. The plant height and root length was measured after nematode inoculation 30 days. The data in the figure are mean ± SE and means on the same column followed by different letters indicate significant differences based on a LSD test (<i>P</i> ≤ 0.05, n = 125).</p

SN101 seed coating inhibited SCN infection under soybean filed conditions in 2013 and 2014.

<p>Plants were treated with biocontrol seed coating-SN101, chemical seed coating-BFA and uncoated-CK. The number of juveniles in roots, cysts in soil and in roots, and eggs per cyst was measured after planted 30–35 days. The data in the figure are mean ± SE and means on the same column followed by different letters indicate significant differences based on a LSD test (<i>P</i> ≤ 0.05). <b>A.</b> the number of cysts per root system (n = 125), <b>B.</b> the number of cysts per 100 g of rhizosphere soil (n = 25), <b>C.</b> the number of juveniles per gram of root (n = 125), <b>D.</b> the number of eggs per cyst (n = 25).</p

Effects of SN101 seed coating on soybean height and root length under filed conditions in 2013 and 2014.

<p>Plants were treated with biocontrol seed coating-sn101, chemical seed coating-BFA and uncoated-CK. The seedling plant height, mature plant height and seedling root length was measured in seedling (after planted 30–35 days) and mature (about after planted 150 days). The data in the figure are mean ± SE and means on the same column followed by different letters indicate significant differences based on a LSD test (<i>P</i> ≤ 0.05, n = 125). <b>A.</b> seedling plant height, <b>B.</b> mature plant height, <b>C.</b> seedling root length.</p