A convergent total synthesis of the kedarcidin chromophore: 20-years in the making

J Antibiot (Tokyo). 2019 Jun;72(6):350-363. doi: 10.1038/s41429-019-0175-y. Epub 2019 Mar 25.

Abstract

The kedarcidin chromophore is a formidible target for total synthesis. Herein, we describe a viable synthesis of this highly unstable natural product. This entailed the early introduction and gram-scale synthesis of 2-deoxysugar conjugates of both L-mycarose and L-kedarosamine. Key advances include: (1) stereoselective allenylzinc keto-addition to form an epoxyalkyne; (2) α-selective glycosylations with 2-deoxy thioglycosides (AgPF6/DTBMP) and Schmidt donors (TiCl4); (3) Mitsunobu aryl etherification to install a hindered 1,2-cis-configuration; (4) atropselective and convergent Sonogashira-Shiina cyclization sequence; (5) Ohfune-based amidation protocol for naphthoic acid; (6) Ce(III)-mediated nine-membered enediyne cyclization and ester/mesylate derivatisation; (7) SmI2-based reductive olefination and global HF-deprotection end-game. The longest linear sequence from gram-scale intermediates is 17-steps, and HRMS data of the synthetic natural product was obtained for the first time.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Cycloparaffins / chemical synthesis*
  • Cycloparaffins / chemistry
  • Enediynes / chemical synthesis*
  • Enediynes / chemistry
  • Molecular Structure
  • Naphthalenes / chemical synthesis*
  • Naphthalenes / chemistry

Substances

  • Antineoplastic Agents
  • Cycloparaffins
  • Enediynes
  • Naphthalenes
  • kedarcidin chromophore