Federico Bernal

Publications (7)73.63 Total impact

• Article: Total synthesis and structural elucidation of azaspiracid-1. Construction of key building blocks for originally proposed structure.

  K C Nicolaou, Petri M Pihko, Federico Bernal, Michael O Frederick, Wenyuan Qian, Noriaki Uesaka, Nicole Diedrichs, Jürgen Hinrichs, Theocharis V Koftis, Eriketi Loizidou, Goran Petrovic, Manuela Rodriquez, David Sarlah, Ning Zou
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  ABSTRACT: Syntheses of the three key building blocks (65, 98, and 100) required for the total synthesis of the proposed structure of azaspiracid-1 (1a) are described. Key steps include a TMSOTf-induced ring-closing cascade to form the ABC rings of tetracycle 65, a neodymium-catalyzed internal aminal formation for the construction of intermediate 98, and a Nozaki-Hiyama-Kishi coupling to assemble the required carbon chain of fragment 100. The synthesized fragments, obtained stereoselectively in both their enantiomeric forms, were expected to allow for the construction of all four stereoisomers proposed as possible structures of azaspiracid-1 (1a-d), thus allowing the determination of both the relative and absolute stereochemistry of the natural product.
  Journal of the American Chemical Society 03/2006; 128(7):2244-57. · 9.91 Impact Factor
• Article: Total synthesis and structural elucidation of azaspiracid-1. Synthesis-based analysis of originally proposed structures and indication of their non-identity to the natural product.

  K C Nicolaou, David Y-K Chen, Yiwei Li, Noriaki Uesaka, Goran Petrovic, Theocharis V Koftis, Federico Bernal, Michael O Frederick, Mugesh Govindasamy, Taotao Ling, Petri M Pihko, Wenjun Tang, Stepan Vyskocil
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  ABSTRACT: The key building blocks (6, 7, and 8) for the intended construction of the originally proposed structures of azaspiracid-1, a potent marine-derived neurotoxin, were coupled and the products elaborated to the targeted compounds (1a,b) and their C-20 epimers (2 and 3). The assembly of the three intermediates was accomplished by a dithiane-based coupling reaction that united the C(1)-C(20) (7) and C(21)-C(27) (8) fragments, followed by a Stille-type coupling which allowed the incorporation of the C(28)-C(40) fragment (6) into the growing substrate. Neither of the final products (1a,b) matched the natural substance by TLC or (1)H NMR spectroscopic analysis, suggesting one or more errors in the originally proposed structure for this notorious biotoxin.
  Journal of the American Chemical Society 03/2006; 128(7):2258-67. · 9.91 Impact Factor
• Article: Total synthesis of the proposed azaspiracid-1 structure, part 1: construction of the enantiomerically pure C1-C20, C21-C27, and C28-C40 fragments.

  K C Nicolaou, Yiwei Li, Noriaki Uesaka, Theocharis V Koftis, Stepan Vyskocil, Taotao Ling, Mugesh Govindasamy, Wenyuan Qian, Federico Bernal, David Y-K Chen
  Angewandte Chemie International Edition 09/2003; 42(31):3643-8. · 13.45 Impact Factor
• Article: Synthesis of the ABCD Ring System of Azaspiracid We thank Drs. D. H. Huang and G. Siuzdak for NMR spectroscopic and mass spectrometric assistance, respectively. This work was financially supported by the National Institutes of Health (USA), The Skaggs Institute for Chemical Biology, a predoctoral fellowship from Bristol-Myers Squibb (to F.B.), postdoctoral fellowships from The Skaggs Institute for Research (to W.Q.), the Academy of Finland, the Ella and Georg Ehrnrooth Foundation and the Tauno T

  K. C. Nicolaou, Wenyuan Qian, Federico Bernal, Noriaki Uesaka, Petri M. Pihko, Jürgen Hinrichs
  Angewandte Chemie International Edition 12/2001; 40(21):4068-4071. · 13.45 Impact Factor
• Article: Synthesis of the ABCD Ring System of Azaspiracid

  K. C. Nicolaou, Wenyuan Qian, Federico Bernal, Noriaki Uesaka, Petri M. Pihko, Jürgen Hinrichs
  Angewandte Chemie International Edition 10/2001; 40(21):4068 - 4071. · 13.45 Impact Factor
• Article: Synthesis of the FGHI Ring System of Azaspiracid We thank Dr. D. H. Huang and Dr. G. Siuzdak for NMR spectroscopic and mass spectrometric assistance, respectively. Financial support for this work was provided by The Skaggs Institute for Chemical Biology, the National Institutes of Health (USA), a predoctoral fellowship from Bristol-Myers Squibb (F.B.), postdoctoral fellowships from the Academy of Finland, the Ella and Georg Ehrnrooth Foundation, and the Tauno Tönning Foundation (all to P.M.P.),

  K. C. Nicolaou, Petri M. Pihko, Nicole Diedrichs, Ning Zou, Federico Bernal
  Angewandte Chemie International Edition 06/2001; 40(9):1573. · 13.45 Impact Factor
• Article: Synthesis of the FGHI Ring System of Azaspiracid

  K. C. Nicolaou, Petri M. Pihko, Nicole Diedrichs, Ning Zou, Federico Bernal
  Angewandte Chemie 03/2001; 113(7):1302 - 1305.