Naturally occurring compounds containing

Many naturally occurring compounds contain several chirality centers By an analysis similar to that described for the case of two chirality centers it can be shown that the maximum number of stereoisomers for a particular constitution is 2" where n is equal to the number of chirality centers... 

There are many abundant naturally occurring compounds containing a pyrrolidine ring system. Remarkably, however, syntheses of kainoids from such materials have received relatively little attention. An important... 

Many naturally occurring compounds contain more than one functional group. Identify the functional groups in the following compounds ... 

Those naturally occurring compounds containing benzo[fc]furan, dihydrobenzo[fc]furan or dihydrobenzo[c]furan skeletons, whose biologicd activities have been assessed are... 

Naturally occurring compounds containing the C-glycosidic linkage... 

References on those naturally occurring compounds containing benzo f>Jfuran or dihydrobenzo[ )]furan skeletons whose biological activities were assessed are <04H(63)879> and <04P3021>. 

A vast array of chiral auxiliaries have been derived from naturally occurring compounds containing the bicyclo[2.2.1]heptane unit (for review articles, see refs 1 -3). In all cases, the ultimate sources of these auxiliaries are the ketones camphor and fenchone, and the alcohols borneol and fenchol, as at least one enantiomer of each compound is provided in enantiomericaUy pure form by nature. Thus. ( + )-camphor [( + )-2], (-)-borneol [(-)- ], and (+)-fenchonc [( + )-5] are enan-tiomerically pure, convenient and inexpensive starting materials for organic synthesis and deriva-tization to give chiral auxiliaries. Most other compounds of this series are also commercially available, but can be prepared by oxidation or reduction of inexpensive precursors by standard methods. The evo-alcohols, such as the enantiomeric isoborneols, are accessible by standard complex hydride reductions of the ketones. The interconnection between these compounds is shown diagrammatically. 

It should be emphasized that the first naturally-occurring compound containing vanadium, with unspecified biological activity was the blue substance amavadine (16) isolated from a mushroom (Amanita muscaria) (75). ESR studies showed that it was a complex of N-hy-... 

Fig. 5. Naturally occurring compounds containing a cyclopentene ring.

The active ingredient that makes tea and coffee valuable to humans is caffeine. Caffeine is an alkaloid, a class of naturally occurring compounds containing nitrogen and having the properties of an organic amine base (alkaline, hence, alkaloid). Tea and coffee are not the only plant sources of caffeine. Others include kola nuts, mate leaves, guarana seeds, and, in small amount, cocoa beans. The pure alkaloid was first isolated from coffee in 1821 by the French chemist Pierre Jean Robiquet. 

Chile saltpeter A naturally occurring compound containing sodium nitrate... 

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