1424352-53-3Relevant academic research and scientific papers
Towards stereochemical control: Two approaches for the highly anti-diastereoselective construction of the spirolactone moieties of some Stemona alkaloids
Tuo, Shichuan,Liu, Xuekui,Huang, Peiqiang
, p. 55 - 62 (2013)
Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration (C-9/C-9a). In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and β-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an α-directing (chelation) group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate afforded spiro-α-methylene-γ-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/ pyrrolidine moieties. In addition, on the basis of our previous work, the total synthesis of (-)-9-epi-11-demethylsessilifoliamide J (11), and an improved synthesis of (-)-9,11-di-epi-sessilifoliamide J (9) were accomplished. Completely anti-diastereoselective: This can be achieved by using bromine atom as a traceless directing group in the SmI2-mediated reductive coupling of α,β-unsaturated ester with ketones; or by the one-pot reaction of the organozinc reagent generated from bromomethacrylate with ketone. On the basis of these results, two approaches to the spirolactone moiety with anti-configuration (C-9/C-9a) found in some Stemona alkaloids were disclosed. Copyright
