The total synthesis of (-)-cyanthiwigin F by means of double catalytic enantioselective alkylation

Double catalytic enantioselective transformations are powerful synthetic methods that can facilitate the construction of stereochemically complex molecules in a single operation. In addition to generating two or more stereocentres in a single reaction, multiple asymmetric reactions also impart increased enantiomeric excess to the final product in comparison with the analogous single transformation. Furthermore, multiple asymmetric operations have the potential to independently construct several stereocentres at remote points within the same molecular scaffold, rather than relying on pre-existing chiral centres that are proximal to the reactive site. Despite the inherent benefits of multiple catalytic enantioselective reactions, their application to natural product total synthesis remains largely underutilized. Here we report the use of a double stereoablative enantioselective alkylation reaction in a concise synthesis of the marine diterpenoid (-)-cyanthiwigin F (ref. 8). By employing a technique for independent, selective formation of two stereocentres in a single stereoconvergent operation, we demonstrate that a complicated mixture of racemic and meso diastereomers may be smoothly converted to a synthetically useful intermediate with exceptional enantiomeric excess. The stereochemical information generated by means of this catalytic transformation facilitates the easy and rapid completion of the total synthesis of this marine natural product

Motivação nas aulas de Educação Física no ensino médio

The study aimed to determine the aspects that motivate students to participate in physical education classes in high school of public schools in the city of Imbituva­PR, as participation in physical education classes. The study included 108 students of both genders. The instrument was a questionnaire with closed and open questions. The data were analyzed descriptively qualitative. The results show that students would feel more motivated with diverse classes, because most aspects of motivation to lack of school structure and classes and repetitive content. It follows that students feel motivated by aspects related to health, sports, new content and diverse classes and unmotivated with aspects related to the lack of school structure and repetitive lessons.O estudo teve como objetivo verificar os aspectos que motivam os alunos para participação nas aulas de Educação Física no ensino médio da rede pública de ensino da cidade de Imbituva­PR, quanto à participação nas aulas de Educação Física. Participaram do estudo 108 alunos de ambos os gêneros. O instrumento utilizado foi um questionário composto por questões fechadas e abertas. Os dados foram analisados de forma qualitativa descritiva. Os resultados evidenciam que os alunos se sentiriam mais motivados com aulas diversificadas, apontando como principais aspectos de desmotivação a falta de estrutura da escola e as aulas e conteúdos repetitivos. Conclui­se, que os alunos se sentem motivados por aspectos relacionados à saúde, esportes, conteúdos novos e aulas diversificadas e desmotivados com aspectos relacionados à falta de estrutura da escola e aulas repetitivas

Chirality in amino acids beyond the C α configuration

Based on a CSD search, a meta-analysis of 1179 structures of 19 natural amino acids H3NC alpha H(R)C '(O)O and their derivatives H3NC alpha H(R)C '(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that the chirality chain with its two steps, established in the preceding paper for alanine, can be extended to natural amino acids. High diastereoselectivities are observed in the induction from the L configuration at C-alpha to the -psi and +psi conformations, which in turn distort the planar carboxylic group C alpha C '(O-cis)O-trans to asymmetric flat tetrahedra, showing that the chirality chain is an integral part of natural amino acids

Resolution of the Chiral (1 R,2S) Enantiomer of cis-Cyclohexane-1,2-dicarboxylic Acid in the Brucinium Salt 2,3-Dimethoxy-10-oxostrychnidinium (1 R,2S)-2-carboxycyclohexane-1-carboxylate Dihydrate

The structure of the 1:1 brucinium salt of cis-cyclohexane-1,2-dicarboxylic acid, 2,3-dimethoxy-10-oxostrychnidinium (1R,2S)-2-carboxycyclohexane-1-carboxylate dihydrate, has revealed the resolved (1R,2S) enantiomer of the acid. Crystals of the compound are orthorhombic, space group P212121, with unit cell dimensions a = 8.1955(3), b = 12.4034(3), c = 29.9073(9)Å, and Z = 4. The asymmetric unit comprises the brucinium cation, the hydrogen cis-cyclohexane-1,2-dicarboxylate cation, in which the carboxylate group is disordered over two sites (58, 42%), and two water molecules of solvation, one of which is occupies two 50% occupancy sites. The classic undulating brucinium cation substructures are present with the anion and the water molecules occupying the interstitial cavities and are hydrogen-bonded to them in a two-dimensional network structure