Original discoveries

The original discovery and classification of DA receptors was based on the results of three distinct studies ... 

Diels-Alder reactions are one of the most fundamental and useful reactions in synthetic organic chemistry. Various dienes and dienophiles have been employed for this useful reaction.1 Nitroalkenes take part in a host of Diels-Alder reactions in various ways, as outlined in Scheme 8.1. Various substituted nitroalkenes and dienes have been employed for this reaction without any substantial improvement in the original discovery of Alder and coworkers.2 Nitrodienes can also serve as 4ti-components for reverse electron demand in Diels-Alder reactions. Because the nitro group is converted into various functional groups, as discussed in Chapters 6 and 7, the Diels-Alder reaction of nitroalkenes has been frequently used in synthesis of complex natural products. Recently, Denmark and coworkers have developed [4+2] cycloaddition using nitroalkenes as heterodienes it provides an excellent method for the preparation of heterocyclic compounds, including pyrrolizidine alkaloids. This is discussed in Section 8.3. 

A wide range of nanosfructured carbons has been discovered since fhe original discovery of carbon nanotubes (CNTs) by lijima in 1991. Carbon nanotubes and nanofibers are nanoscale cylinders of rolled up graphene sheets. 

Taube s original discovery/ Attendant changes of redox rates by many orders of magnitude have been observed. Much data have been obtained on reactions of the type... 

Mineialogists long remained in doubt as to the existence of petahte until E. T. Svedenstjerna rediscovered it in 1817 on Uto (an island in Sweden), thus confirming the original discovery by de Andrada (36). 

All Group VIII metals, as well as Mn, Cr, and Cu, exhibit some activity in hydroformylation.6 11 Cobalt, the catalyst in the original discovery, is still used mainly in industry rhodium, introduced later, is one of the most active and studied catalysts. The metal catalysts may be applied as homogeneous soluble complexes, heteroge-nized metal complexes, or supported metals. 

The effect of hollowed charges appears to have been redis( covered, probably independently, by Egon Neumann, who claimeexplosive technique was patented by the Westfalisch-Anhaltische Sprengstoff-... 

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