Natural products enol-containing

Aryl ethers were also coupled intramolecularly with enol ethers when vinylsulfide was used as initiator of the coupling reaction the selectivity could be improved considerably [172e]. Additionally, the coupling to furan rings was studied, which led to advanced intermediates for the synthesis of bicyclic furan-containing natural products [172e],... 

Asymmetric syn and anti aldol reactions have been used for synthesis of the following natural products containing lactone moieties. A titanium enolate-based aldol reaction has also been utilized in the aldol dehydration sequence during the synthesis of pyrone natural products mxyopyronin A and B. The following syntheses of lactone-containing natural products highlight the variety of aldol transformations. 

The enol ether double bond contained within the ds-fused dioxa-bicyclo[3.2.0]heptene photoadducts can also be oxidized, in a completely diastereoselective fashion, with mCPBA. Treatment of intermediate XXII, derived in one step from a Patemo-Buchi reaction between 3,4-dimethylfuran and benzaldehyde, with mCPBA results in the formation of intermediate XXIII. Once again, consecutive photocycloaddition and oxidation reactions furnish a highly oxygenated system that possesses five contiguous stereocenters, one of which is quaternary. Intermediate XXIII is particularly interesting because its constitution and its relative stereochemical relationships bear close homology to a portion of a natural product known as asteltoxin. 

In addition to the above examples, there are still a large number of bioactive natural products and various synthetic and semisynthetic enol-containing compounds that serve as potential and promising drugs for various therapeutic purposes such as the non-peptidyl HIV inhibitor Aptivus (tipranavir Section IV.1) and the third-generation tetracycline antibiotics (Section IV.H). The structure and function of the metal complexes of some... 

Dutch elm disease is a fungal disease, carried by elm bark beetles, which devastated the elm populations of many parts of the world in the 1970s. The beetles assemble at a suitable elm tree on the call of a pheromone containing, among compounds derived from the tree, one charactacteristic of the beetle itself, multistriatin 48. The stereochemistry of this compound was deduced by the synthesis of the various possible isomers as so little natural product was available.8 We shall use three of these syntheses to illustrate the application of aza-enolates to alkylation reactions. 

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