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A massive open online course (MOOC), Exploring Everyday Chemistry (eeDc), was delivered four times between 2017 and 2019, attracting a worldwide audience of over 15â¯000 learners from a wide range of backgrounds. This 4-week course was designed to show a variety of everyday applications of organic chemistry, targeted at high school students seeking to study a chemistry-related degree at university. A mix of video, text, polls, quizzes, and practical activities was incorporated with material designed to build on high school studies, highlighting aspects of university-level teaching and research, as well as showcasing some career opportunities for chemistry graduates. We monitored student attitudes toward this course, finding a consistent enthusiasm for the approach and selection of material. The impact of the course was evident from the significant number of students who mentioned it positively in their university applications.
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Sustainable practices in process chemistry are highlighted by a novel, 9 week team project of 8-12 students, in collaboration with AstraZeneca chemists, in an organic chemistry laboratory. Students synthesize the antiulcer medicine esomeprazole, which involves the asymmetric oxidation of pyrmetazole. To provide insight into the modern process chemistry industry, they propose environmentally friendly modifications to the asymmetric oxidation. Students first synthesize pyrmetazole and then follow a standard oxidation procedure and carry out modified, greener reactions of their choice. They investigate how a change in reaction conditions affects both the yield and enantioselectivity of esomeprazole. Positive student feedback was received and student postlab reports were analyzed over a 4 year period (2015-2018). Results consistently showed that the project provided students with the key tools to develop greener syntheses. This contextual approach not only offers the opportunity to develop valuable communication and team-working skills, but it also gives students creative input into their experimental work. It teaches the important research skills involved in sustainable process chemistry, from reproducing and modifying a literature procedure to identifying green metrics.
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A new practical route to chaetomellic acid A (ACA), based on the copper catalysed radical cyclization (RC) of (Z)-3-(2,2-dichloropropanoyl)-2-pentadecylidene-1,3-thiazinane, is described. Remarkably, the process entailed: (i) a one-pot preparation of the intermediate N-α-perchloroacyl-2-(Z)-alkyliden-1,3-thiazinanes starting from N-(3-hydroxypropyl)palmitamide, (ii) a two step smooth transformation of the RC products into ACA and (iii) only one intermediate chromatographic purification step. The method offers a versatile approach to the preparation of ACA analogues, through the synthesis of an intermediate maleic anhydride with a vinylic group at the end of the aliphatic tail, a function that can be transformed through a thiol-ene coupling. Serendipitously, the disodium salt of 2-(9-(butylthio)nonyl)-3-methylmaleic acid, that we prepared as a representative sulfurated ACA analogue, was a more competent FTase inhibitor than ACA. This behaviour was analysed by a molecular docking study.
Assuntos
Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Farnesiltranstransferase/antagonistas & inibidores , Maleatos/química , Maleatos/farmacologia , Animais , Catálise , Cobre/química , Ciclização , Inibidores Enzimáticos/síntese química , Farnesiltranstransferase/metabolismo , Maleatos/síntese química , Simulação de Acoplamento Molecular , Ratos , Leveduras/enzimologiaRESUMO
[reaction: see text] Addition of diethyl thiophosphite to terminal alkenes, in the presence of a radical initiator, followed by deprotonation of the phosphonothioate and reaction with a ketone, offers a concise one-pot approach to substituted alkenes. This novel method, which can incorporate alkylation or acylation steps, can be applied to the stereoselective formation of sterically hindered tri- and tetrasubstituted alkenes.
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The chemistry of Erythrina and related alkaloids from 1996 through to mid-2009 has been reviewed, with a particular focus on the preparation of Erythrina alkaloids possessing an aromatic D ring. A number of synthetic approaches to alkaloids bearing an aromatic D ring have been reported, including some asymmetric routes. Recent studies have explored strategies toward Erythrina alkaloids possessing a nonaromatic D ring, although, as yet, few total syntheses have been published.
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Alcaloides/química , Erythrina/química , Inseticidas/síntese química , Fitoterapia , Alcaloides/síntese química , Alcaloides/farmacologia , Ciclização , Di-Hidro-beta-Eritroidina/síntese química , Di-Hidro-beta-Eritroidina/química , Alcaloides Indólicos/síntese química , Alcaloides Indólicos/química , Inseticidas/química , Inseticidas/farmacologia , Estrutura MolecularRESUMO
A new, concise, and flexible approach to novel quinuclidines has been developed, which employs a phosphorus hydride mediated radical addition/cyclization reaction in the key step. 1,7-Diene 5 reacts with diethyl thiophosphite in an efficient and diastereoselective radical addition/cyclization reaction to give trisubstituted piperidines 4ab. Piperidines 4ab are subsequently converted into 2,5-disubstituted quinuclidines using S(N)2-type cyclizations. Finally, the resulting quinuclidines are shown to undergo novel Horner-Wadsworth-Emmons-type (HWE-type) reactions to give unsaturated quinuclidines 21a and 21b, which have structures similar to that of (-)-quinine 1.
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Quinuclidinas/síntese química , Ciclização , Radicais Livres/química , Quinuclidinas/química , EstereoisomerismoRESUMO
For many years, the reputed lack of selectivity in some free-radical reactions has resulted in this class of reaction being overlooked in the stereoselective synthesis of important target molecules. More recently, however, the situation has changed as new and milder methods of radical generation have been developed, which have helped researchers to gain a better understanding of the key factors that influence selectivity in radical transformations. As a consequence, the use of radicals in stereoselective synthesis is increasing and there are a number of important intra- and intermolecular additions, where high levels of stereoselectivity have been achieved in the formation of carbon-carbon bonds.
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beta-Keto esters and beta-keto amides can be efficiently alkylated on reaction with enol ethers and manganese(III) acetate in the presence of copper(II) acetate. These intermolecular radical addition reactions can be used to construct quaternary carbon centres in excellent yield and this method has been utilised in a diastereoselective approach to substituted pyrrolidinones.