62948-37-2Relevant academic research and scientific papers
Phyllanthoside-Phyllanthostatin Synthetic Studies. 7. Total Synthesis of (+)-Phyllanthocin and (+)-Phyllanthocindiol
Smith III, Amos B.,Fukui, Mineo,Vaccaro, Henry A.,Empfield, James R.
, p. 2071 - 2092 (2007/10/02)
A stereochemically linear total synthesis of (+)-phyllanthocin (5a), the aglycon methyl ester of the antineoplastic glycoside (+)-phyllanthoside (1), is described. The synthesis proceeds in 23 steps (4.5% overall yield) and affords (+)-phyllanthocin in high enantiomeric purity. The central features of the strategy include: (a) construction of aldehyde 8 via a stereoselective, intramolecular ene reaction; (b) elaboration of the spiroketal unit by a two-step tactic involving addition of a functionalized dihydropyran anion (i.e., 9) to 8, followed by a highly stereoselective spiroketalization; and (c) chemo- and stereoselective methylenation of the C(7) carbonyl group. In addition, a second-generation approach is presented, wherein an augmented spiroketalization maneuver not only establishes the C(8) spirocenter but also permits the regio- and stereocontrolled introduction of the C(11) methyl group. The latter sequence furnishes (+)-phyllanthocin in 21 steps (5.6% overall yield). Finally, the advanced phyllanthocin intermediate (+)-49 is converted in five steps (42% overall yield) to (+)-phyllanthocindiol (5b), the aglycon of phyllanthostatin 3.
Total Synthesis of (+)-Phyllanthocin. Introduction of Intramolecular Hydroformylation for Complex Molecule Functionalization
Burke, Steven D.,Cobb, Jeffery E.,Takeuchi, Kumiko
, p. 2138 - 2151 (2007/10/02)
A 17-step total synthesis of (+)-phyllanthocin (1a) is described.Application of Sharpless'asymetric epoxidation reaction provided access to the diastereo- and enantiomerically pure epoxy ketone 9, a partner in crossed aldol construction.A notably rapid and high-yielding spiroketal equilibration leading to the tetracyclic intermediate 2 was effected with HF in acetonitrile.A Rh(I)-catalyzed hydroformylation was used to introduce the C3 functionality.Studies of intramolecular delivery of the rhodium nucleus to the concave face of the C3-C4 olefin led to a substantial improvement in yield and regioselectivity over the intermolecular version.
TOTAL SYNTHESIS OF ( plus )-PHYLLANTHOCIN.
Williams,Sit
, p. 2949 - 2954 (2007/12/18)
Investigations culminating in the total synthesis of ( plus )-phyllanthocin via a highly convergent route beginning with natural tartaric acid are reported. The stereochemical consequences of internal spiroketalization with protic acid and Lewis acid chel
The structures of phyllanthostatin 1 and phyllanthoside from the Central American tree Phyllanthus acuminatus Vahl
Pettit, George R.,Cragg, Gordon M.,Gust, Devens,Brown, Peter,Schmidt, Jean M.
, p. 939 - 941 (2007/10/02)
A new antineoplastic glycoside, phyllanthostatin 1, and the related glycoside, phyllanthoside, have been isolated from the Central American tree, Phyllanthus acuminatus Vahl.The structures of phyllanthostatin (1a) and phyllasthoside (1b) were completely assigned by analyses of spectral data, principally by high resolution (400 MHz) nmr.In addition to exhibiting activity against the National Cancer Institute's P388 lymphocytic leukemia, phyllanthoside was found to possess a curative level of activity against the murine B16 melanoma.
