A versatile synthesis of functionalized pentahelicenes

J Org Chem. 2010 Oct 15;75(20):6889-99. doi: 10.1021/jo1013977.

Abstract

A general synthetic methodology for the preparation of functionalized (hetero)helicenes has been developed. It employs the sequence of a double propargyl organometallics (Li, Mg, Ga/In) addition to a tolan-2,2'-dialdehyde-type intermediate, a cobalt-catalyzed/cobalt-mediated [2 + 2 + 2] cycloisomerization of a triyne intermediate, and a double silica gel-assisted acetic acid elimination to receive pentahelicene, 1,14-diazapentahelicene, and 3,12-dichloro-, 3,12-dichloro-7-trimethylsilyl-, and 3,12-di-tert-butylpentahelicene. 3,12-Dichloropentahelicene undergoes a Suzuki-Miyaura coupling with aryl boronic acids (or ester) under palladium catalysis to afford 3,12-diarylpentahelicenes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkynes / chemistry*
  • Catalysis
  • Crystallography, X-Ray
  • Cyclization
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemistry
  • Polycyclic Compounds / chemical synthesis*
  • Polycyclic Compounds / chemistry
  • Stereoisomerism

Substances

  • Alkynes
  • Organometallic Compounds
  • Polycyclic Compounds
  • helicenes