Effects of surface application of dolomitic limestone and calcium-magnesium silicate on soybean and maize in rotation with green manure in a tropical region

Although lime is currently the material most frequently used to ameliorate soil acidity in Brazil, silicate could efficiently replace this source because of its greater solubility and its greater silicon content, which are beneficial for plant development. This study aimed to evaluate the effects of superficial lime and silicate application on soil chemical attributes as well as on soybean and maize nutrition and grain yields when these crops are grown in rotation with green manure. The experimental design was a complete randomized block with sixteen replicates. Plots were treated with one of two materials for acidity correction (dolomitic lime and calcium/magnesium silicate) or with no soil correction, as a control. Silicate corrected soil acidity and increased exchangeable base levels in soil at greater depths faster than does liming. The application of both acidity-correcting materials increased N, Ca and Mg leaf concentrations, and all yield components and grain yield in soybean; but in maize, just silicate also increased N and Si when compared with lime, whereas both acidity-correcting increased just two yield components: grains per ear and mass of 100 grains, resulting in highest grain yield. The application of both acidity-correcting materials increased dry matter production of green manures, but for pigeon pea the silicate provided the best result in this dry-winter region.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ)Embrapa Amapá, Transferência de TecnologiaUniversidade Estadual Paulista Júlio de Mesquita Filho Departamento de Produção VegetalUniversidade Estadual Paulista Júlio de Mesquita Filho Departamento de Produção VegetalFAPESP: 2006/01705-

Modern strategies for C–H functionalization of heteroarenes with alternative coupling partners

Heteroarenes containing oxygen, nitrogen, and/or sulfur are important in numerous aspects of chemistry and everyday life. C–H functionalization of heteroarenes represents the fastest and most atom-economical approach for the synthesis of complex molecules. This strategy avoids the requirement of de novo synthesis and is beneficial for the late-stage modification of structurally complex molecules. Although early protocols for C–H functionalization using organic halides (I, Br, and Cl) as coupling partners remain in active use today, a range of modern strategies allows the cleavage of less reactive C–Het (F, O, S, N, and P) and C–C bonds to form essential links to the feedstock chemicals, highlighting their renewable and sustainable features. This review focuses on modern strategies for the C–H functionalization of heteroarenes with these alternative coupling partners. Most of the transformations can be achieved through catalytic processes. Some non-catalytic strategies involving new reagents and techniques are also introduced

Site-selective C–H functionalization to access the arene backbone of indoles and quinolines

The site-selective C–H bond functionalization of heteroarenes can eventually provide chemists with great techniques for editing and building complex molecular scaffolds.</jats:p

Cyclization and Cycloisomerization of π-Tethered Ynamides: An Expedient Synthetic Method to Construct Carbo- and Heterocycles

Stable ynamides are used for the development of novel synthetic transformations and the construction of unusual carbo/heterocycles. The intramolecular cyclization of π-tethered alkene/alkyne/allene-ynamides is studied extensively for the fabrication of a wide range of molecular scaffolds for various applications. The ketene-acetal/aminal generated in situ from π-tethered ynamides participates in intramolecular cyclization/cycloisomerization processes to yield N-bearing fused heterocycles. This account summarizes the scientific merits and the advances made in cyclization and cycloisomerization strategies for stable π-tethered alkene/alkyne/allene-ynamides.1 Introduction2 π-Tethered Ynamides3 Alkene-Tethered Ynamides4 Alkyne-Tethered Ynamides5 Allene-Tethered Ynamides6 Concluding Remarks</jats:p

Gold-catalyzed cyclization and cycloisomerization of yne-tethered ynamide: the significance of a masked enol-equivalent of an amide

The enol-equivalent of an amide: a tool useful to construct novel N-heterocycles.</p