73968-62-4Relevant articles and documents
Total Synthesis of Belizentrin Methyl Ester: Report on a Likely Conquest
Anderl, Felix,Gr??l, Sylvester,Wirtz, Conny,Fürstner, Alois
, p. 10712 - 10717 (2018/08/17)
The assigned structure of the dinoflagellate-derived toxin belizentrin was prepared by total synthesis in form of the corresponding methyl ester for stability reasons. The successful route features an unusual solution for the preparation of a recalcitrant ylide on a C-glycosidic segment; moreover, it involves an asymmetric hetero-Diels–Alder reaction en route to the tertiary hemiacetal substructure, a Negishi cross-coupling of two elaborate building blocks, and a macrocyclization based on an intramolecular aminolysis of a spirolactone. A modified Kocienski olefination ultimately allowed the polyol side chain to be attached to the macrocycle although this transformation faced the exceptional base sensitivity of this polyunsaturated target compound.
Novel peptides comprising furanoid sugar amino acids for the treatment of cancer
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, (2010/02/10)
Anticancer peptides which incorporate furanoid sugar amino acids and compositions made using these peptides are described. Methods for synthesis of the peptides and for preparing the furanoid sugar amino acids are disclosed. The peptides and compositions made using the peptides have pharmacological applications of these peptides especially in the treatment and prevention of cancer and tumors.
Enantioselective synthesis of key intermediates in a novel approach towards the Iboga-alkaloid family
Hoeck, Stefan,Borschberg, Hans-Juerg
, p. 1397 - 1409 (2007/10/03)
Significant improvements in the realm of a recently disclosed, novel synthetic concept towards the Iboga alkaloid family are presented. The key step for the construction of the bicyclic aliphatic core consists of an intramolecular nitrone-olefin 1,3-dipolar cycloaddition reaction of a 1:1 mixture 15/16 yielding the two diastereoisomeric tricyclic isoxazolidine derivatives 17 and 18. The required nitrones were prepared from the readily available (S)-hydroxylactone 6 in twelve steps with an oyerall yield of 15% (average: 83.5% per step). The relative configuration of the minor isomer was deduced unambiguously by single-crystal X-ray analysis of the derived tricyclic carbamate 21. As four out of five asymmetric centers in the pair 17/18 have opposite configuration, destruction of the one possessing the same absolute configuration transforms the original set of diastereoisomers into a pair of enantiomers. We verified this contention by oxidizing the two alcohols 20 and 22 to yield the two antipodal forms of ketone 23. The absence of significant amounts of by-product and the high reproducibility of the crucial cycloaddition reaction represent marked improvements over our earlier attempts. In addition, the new route, which starts from L-glutamate, should provide access to both naturally occurring antipodal series of the targeted alkaloid class.
