Synthesis of Chromen[4,3-b]pyrrolidines by Intramolecular 1,3-Dipolar Cycloadditions of Azomethine Ylides: An Experimental and Computational Assessment of the Origin of Stereocontrol

Azomethine ylides, generated from imine-derived O-cinnamyl or O-crotonyl salicylaldeyde and α-amino acids, undergo intramolecular 1,3-dipolar cycloaddition, leading to chromene[4,3-b]pyrrolidines. Two reaction conditions are used: (a) microwave-assisted heating (200 W, 185 °C) of a neat mixture of reagents, and (b) conventional heating (170 °C) in PEG-400 as solvent. In both cases, a mixture of two epimers at the α-position of the nitrogen atom in the pyrrolidine nucleus was formed through the less energetic endo-approach (B/C ring fusion). In many cases, the formation of the stereoisomer bearing a trans-arrangement into the B/C ring fusion was observed in high proportions. Comprehensive computational and kinetic simulation studies are detailed. An analysis of the stability of transient 1,3-dipoles, followed by an assessment of the intramolecular pathways and kinetics are also reported.Financial support was provided by the Brasilian Universiade Federal do Rio de Janeiro (UFRJ), the Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), by the Spanish Ministerio de Ciencia e Innovación (MICINN) (projects CTQ2010-20387, Consolider Ingenio 2010, CSD2007-00006), the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P, CTQ2014-51912-REDC, and CTQ2013-45415-P), the Fondos Europeos para el Desarrollo Regional (FEDER), the Generalitat Valenciana (PROMETEO 2009/039 and PROMETEOII/2014/017), the Basque Government (GV/EJ, grant IT-324-07), and the Universities of Alicante and of the Basque Country (UPV/EHU) (UFI11/22 QOSYC)

Avaliação dos efeitos de fontes de fósforo na dieta sobre parâmetros do meio ruminal e eficiência de síntese microbiana, digestibilidade dos nutrientes e fósforo plasmático em bovinos Evaluation of different phosphorus sources in the diet on ruminal parameters, microbial synthesis, nutrient apparent digestibility and plasma phosphorus in cattle

Este trabalho foi conduzido com os objetivos de avaliar o efeito de fontes de fósforo em dietas para bovinos em crescimento sobre o coeficiente de digestibilidade parcial e total dos nutrientes, os parâmetros ruminais, a eficiência de síntese microbiana e os níveis plasmáticos de fósforo. Foram utilizados quatro bovinos castrados, raça Holandesa Preto e Branco (280 kg de peso vivo), com cânula ruminal e duodenal, em delineamento quadrado latino 4 &#215; 4, com quatro fontes de fósforo (fosfato bicálcico - BIC; superfosfato triplo - SPT; fosfato monoamônio - MAP; e fosfato de rocha Araxá - FRA). As fontes de fósforo não afetaram a ingestão, o fluxo fecal, as digestibilidades ruminal, duodenal e total de matéria seca, matéria orgânica, proteína bruta, fibra em detergente neutro e carboidratos não-fibrosos. A absorção de fósforo do fosfato de rocha Araxá foi menor e diferiu da absorção do fosfato bicálcico e do fosfato monoamônio. Os animais que receberam fosfato de rocha Araxá apresentaram maiores ingestão, fluxo fecal, fluxo duodenal, desaparecimento ruminal e desaparecimento fecal de flúor (F). A utilização de fosfato de rocha Araxá resultou em níveis de flúor na dieta superiores aos recomendados para evitar sua toxidez. As fontes de fósforo não alteraram os níveis plasmáticos de fósforo nem a ingestão de nitrogênio, a eficiência de síntese microbiana e a composição das bactérias ruminais. Também não influenciaram o pH ruminal e as concentrações de NH3-ruminal. Estes resultados indicam que é possível o uso do superfosfato triplo e do fosfato monoamônio em substituição ao fosfato bicálcico.<br>This study was carried out to evaluate the effects of different phosphorus sources, in diets of growing cattle, on apparent partial and total nutrient digestibility; ruminal parameters; microbial efficiency synthesis and plasma phosphorus. Four Holstein steers weighting 280 kg and implanted with ruminal and duodenal cannulas were used. The experimental design was a 4 &#215; 4 Latin Square and treatments were four supplemental phosphorus sources in the diet as follows: dicalcium phosphate (DP), supertriple phosphate (SP), monoammonium phosphate (MP) and Araxa rock phosphate (ARP). Phosphorus sources did not affect intake, fecal flow, apparent ruminal and intestinal digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and non fiber carbohydrates (NFC). There was a lower phosphorus apparent absorption for ARP, differing of DP and MP. Animals receiving ARP showed higher intake, fecal flow, duodenal flow, ruminal disappearance and total disappearance for fluoride. Animals receiving ARP presented fluoride levels higher than those acceptable to avoid toxicity. Phosphorus sources did not affect plasma phosphorus, nitrogen intake, microbial efficiency synthesis and ruminal bacteria composition. Treatments did not affect ruminal pH and ruminal ammonia concentration. These results show a possible use for supertriple phosphate and monoammonium phosphate to replace dicalcium phosphate

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora