189347-95-3Relevant academic research and scientific papers
Formal total synthesis of hemibrevetoxin B by an oxiranyl anion strategy
Mori, Yuji,Yaegashi, Keisuke,Furukawa, Hiroshi
, p. 6200 - 6209 (2007/10/03)
The synthesis of the tetracyclic structure of hemibrevetoxin B (1) was achieved through a linear approach involving sequential coupling of three kinds of sulfonyl-stabilized oxiranyl anions, 5b, 6b, and 7b, to the monocyclic tetrahydropyran 4 containing the requisite substituents. Two iterations of alkylation of an oxiranyl anion and 6-endo cyclization provided the 6,6,6-tricyclic ring system 34, which was efficiently transformed into the 6,6,7-ring system 35 by ring expansion using trimethylsilyldiazomethane. Installation of the final oxepane ring into 38 was carried out using a combination of the oxiranyl anion methodology and ring enlargement just described. Stereoselective introduction of a tertiary methyl group into 41 provided the tetracyclic compound 42a, which contains all the asymmetric centers of 1. Elaboration of 42a to the known compound 2, which was already transformed into hemibrevetoxin B, completed the formal total synthesis of the natural product.
Highly Stereoselective Nucleophilic Epoxidation of Simple Vinyl Sulfoxides
Fernández De La Pradilla, Roberto,Castro, Sonia,Manzano, Pilar,Martín-Ortega, María,Priego, Julián,Viso, Alma,Rodríguez, Ana,Fonseca, Isabel
, p. 4954 - 4966 (2007/10/03)
The nucleophilic epoxidation of readily available vinyl and dienyl sulfoxides with MOO-t-Bu (M = Li, Na, K) takes place in good yields, with complete preservation of double bond geometry in most cases and with moderate to excellent diastereofacial selectivity to produce enantio- and diastereomerically pure α,β-epoxy sulfoxides, valuable synthetic intermediates. Subsequent straightforward oxidation at sulfur affords the corresponding enantiopure sulfonyl oxiranes. For (1E)-2-sulfinyl dienes, the facial selectivity of this novel process may be controlled by the choice of metal (Li vs Na).
