11-Step Total Synthesis of Araiosamines, J.
May 2006 - Cheryl Carson successfully completes the total synthesis of phyllantidine in time for the CSC conference.
Soc., 116, 3125-3126 (1994)"TotalSynthesis of (+)-Leinamycin,"Y.
Commun., 32, 869-873 (2002)"Synthesis of2,3-Disubstituted Indoles by Radical Cyclization with HypophosphorousAcid and Its Application to Total Synthesis of (±)-Catharanthine,"Matthew T.
April 2008 - Dr. Ian Young is this year's recipient of the Paul de Mayo Award, honouring the Department's top graduate students. He was temporarily released from his shackles at the Baran Lab at TSRI (La Jolla, CA) for a few days, to present a well-received seminar on the total synthesis of axinellamines A and B. Great work Ian!
11-Step Total Synthesis of Pallambins C and D, J.
December 2006 - Mike Ganton and Ian Young complete total syntheses of CC-1065 CPI subunit and (+)-Nakadomarin A respectively. Congratulations gentlemen! Look for these in full papers in JOC and JACS soon!
Owing to their unusual structural motifs and promising pharmacological properties, colchicine (1) and NCME (2) have attracted considerable attention from synthetic chemists, which has resulted in several elegant total syntheses of 1 and 2. Recently, we developed an enantioselective synthesis of colchicine (1) from commercially available and inexpensive 2,3,4-trimethoxybenzaldehyde (5). The challenging tricyclic 6–7–7 core of colchicinoids was efficiently introduced using an intramolecular oxidopyrylium-mediated [5 + 2] cycloaddition reaction. In our continuing efforts toward the synthesis of biologically active natural products, we herein describe a modified concise and highly enantioselective synthesis of colchicine using the Wacker oxidation for the regioselective construction of the highly oxidized tropolone C-ring. Moreover, asymmetric total syntheses of β-lumicolchicine and NCME were also achieved.
Soc., 114, 383-385 (1992)"TotalSynthesisof (±)-Renieramycin A,"T.
Our synthesis began with the preparation of 6 (>99% ) from 5 in 5 steps in 21.8% overall yield, as reported previously (). The diastereoselective reduction of the ketone group in 6, followed by the chemoselective methylation of the resulting alcohol, afforded 8 in 75% yield (1.0 g scale). The structure of 8 was unambiguously confirmed using X-ray crystallography. After extensive experimentation, we found that the regioselective Wacker oxidation of the substituted olefin using air as a co-oxidant gave ketone 9 in good yield. We reasoned that the methoxy group at C10 in 8 was critical for this regioselective outcome. Finally, the double elimination of the oxa-bridge in 9 proceeded smoothly using a slightly modified version of Cha’s procedure in the presence of TMSOTf and Me2EtN in DCM to complete our total synthesis of (−)-1 in 81% yield in >99% . The 1H and 13C NMR spectra of synthetic 1, as well as its optical rotation, were identical to those of the natural product.
Use of the recently developed direct indole coupling enabled an efficient, practical, scalable, and protecting-group-free synthesis of each of these natural products.
Total Synthesis of Dixiamycin B by Electrochemical Oxidation J.
Natural Product Synthesis in the Age of Scalability, Nat.
For review and selected application of [5 + 2] cycloaddition reaction in natural product synthesis, see:
Scalable EnantioselectiveTotal Synthesis of Taxanes, Nature Chem.
"Total Synthesis of (+)-Yatakemycin," Kentaro Okano, Hidetoshi Tokuyama, and Tohru Fukuyama J.
C–H Functionalization Logic in Total Synthesis, Chem.
Jun Shi – Total Synthesis of Complex Natural Products: Cortistatin A, Vinigrol and Maoecrystal V
Total Synthesis of Palau'amine, Angew.
Subsequently, the proposed transition-metal-catalyzed decarbonylation/electrocyclic ring-opening cascade reaction of 3 was attempted using several different catalysts (Rh, Ni, and Pd) in a variety of different solvents, as reported previously. However, these conditions failed to afford any of the desired product of 2. To our delight, the irradiation of a solution of β-lumicolchicine (3) in 10:1 (v/v) CH3CN/acetone (0.0024 mol/L) with a 125 W high-pressure mercury arc lamp surrounded by a Pyrex water jacket for 20 min gave 2 in 54% yield instead of α-lumicolchicine (4) and colchicine. The outcome of this transformation suggested that under the irradiation compound 3 had probably undergone a decarbonylation process to generate the intermediate B, followed by the anticipated retro-4π-electrocyclization reaction to give 2, which has been reported to exhibit greater inhibitory activity toward tubulin than colchicine. The 1H and 13C NMR spectra of synthetic 2 and 3, as well as their optical rotation, were identical to those of the natural products. We also have tried to extend the time of irradiation for one-pot synthesis of compound 2 from 1, but a trace of 2 was detected. Probably, other unidentified compounds made the reaction more complex, with the time extended and the temperature of the solution increased. So, after many attempts, we found that 25 min is the best time length for the first irradiation and the two-step sequence is more efficient than the one-pot procedure for the preparation of 2 from 1.
Total Synthesis of Vinigrol, J.
A novel direct oxidative coupling reaction between carbonyl groups and indoles was recently developed. Total syntheses of highly functionalized natural products, (+) -hapalindole and (+) -welwitindolinone, were achieved using the new method. The present coupling strategy makes the synthesis of indole alkaloids highly concise and practical.
Enantiospecific Total Syntheses of Kapakahines B and F, J.
Lett., 14, 1946 (2012) (doi: 10.1021/ol3005613) [PDF] [Supporting Information] "Total Synthesis of (–)-Anisatin" Akihiro Ogura, Kohei Yamada, Satoshi Yokoshima, and Tohru Fukuyama Org.
Chemoselectivity: The Mother of Invention in Total Synthesis, Acc.
Lett., 14, 1632 (2012) (doi: 10.1021/ol300390k) [PDF] [Supporting Information](This paper was featured on Synfacts) "Total Syntheses of All the Amathaspiramides"Koji Chiyoda, Jun Shimokawa, Tohru FukuyamaAngew.
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