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Abstract: An Intramolecular Diels‐Alder cycloaddition reaction between a furan diene and an alkynic dienophile was performed within a flow hydrogenator fitted with an inert titanium column at 150 °C, no H<sub>2</sub>, under 100 bar pressure. A single column pass (<i>t</i><sub>R</sub> = 1.6 min) afforded ≈ 55% conversion to the tetrahydroepoxyisoindole carboxamide scaffold with a product turnover of ≈ 0.035 g/h, a 95% improvement over batch procedures. The cycloaddition protocol is performed in water and ethanol, does not require catalysts or other additives. Quantitative hydrogenation of the resulting dual π‐bonds within the oxabicyclo system was effected with either a 10% Pd/Al<sub>2</sub>O<sub>3</sub> or 10% Pd/CaCO<sub>3</sub> catalyst at 20 °C, 20 bar, with full H<sub>2</sub> whereas utilisation of a Raney Ni catalyst under these conditions resulted in a quantitative mono‐olefin reduction of the C4‐C5 double‐bond. With regard to di‐olefin reduction, a degree of stereoselectivity was observed with the aforementioned palladium‐based catalysts yielding exclusive formation of (<i>R</i>) configuration at C7 while utilisation of a 5% Pt/C (sulfided) catalyst at temperatures below 60 °C promoted the formation of the (<i>S</i>)‐isomer at C7. Hence this work further highlights that flow‐hydrogenation provides unprecedented convenience for establishing robust protocols to effect chemoselective transformations.
| Authors: | Lawson Spare, David Harman, Janice Aldrich-Wright, Thanh Nguyen, Christopher Gordon | |
| Journal: | Advanced Synthesis & Catalysis | |
| Year: | 2018 | |
| Pages: | n/a | |
| DOI: | 10.1002/adsc.201701471 | |
| Publication date: | 18-Jan-2018 |
The unfolding landscape of the congenital myasthenic syndromes
Abstract Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is impaired by one or more specific mechanisms. Since the advent of next‐generation sequencing methods, the discovery of novel CMS targets and phenotypes ha ... more
Passive transfer models of myasthenia gravis with muscle‐specific kinase antibodies
Abstract Myasthenia gravis (MG) with antibodies to muscle‐specific kinase (MuSK) is characterized by fluctuating fatigable weakness. In MuSK MG, involvement of bulbar muscles, neck, and shoulder and respiratory weakness are more prominent than in acetylcholine receptor (AChR) MG. MuSK au ... more
Abstract Because of the failure of many promising therapeutics identified in preclinical evaluation, funding sources have established guidelines for increased rigor in animal evaluations. The myasthenia gravis (MG) community of scientists has developed guidelines for preclinical assessme ... more
Smart skin made of recyclable materials may transform medicine and robotics
Smart skin that can respond to external stimuli could have important applications in medicine and robotics. Using only items found in a typical household, researchers have created multi-sensor artificial skin that's capable of sensing pressure, temperature, humidity, proximity, pH, and air ... more
How mercury contamination affects reptiles in the Amazon basin
Mercury contamination in water and on land is of worldwide concern due to its toxic effects on ecosystems and human health. Mercury toxicity is of particular concern to reptiles because they are currently experiencing population declines. Also, reptiles are ideal indicators of mercury conta ... more
Bioengineers Succeed in Producing Plastic Without the use of Fossil Fuels
A team of pioneering South Korean scientists have succeeded in producing the polymers used for everyday plastics through bioengineering, rather than through the use of fossil fuel based chemicals. This groundbreaking research, which may now allow for the production of environmentally consci ... more
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