Synlett 2004(13): 2249-2267  
DOI: 10.1055/s-2004-832847
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

Adventures with Acetylenes: A Personal Odyssey from Wyerone and ­Crepenynic Acid to Enediynes, Acetylenic Cyclophanes, and Propargyl ­Alcohols

Alex G. Fallis*
Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
Fax: +1(613)5625170; e-Mail: afallis@science.uottawa.ca;
Further Information

Publication History

Received 5 June 2004
Publication Date:
24 September 2004 (online)

Abstract

This account provides an overview, in varying depth, of our research into diverse aspects of acetylene chemistry over the last three decades. Initial studies with acetylenic natural products (Wyerone, Crepenynic Acid) were followed several years later with synthetically oriented projects. These involved enediyne mimics of natural products (Taxamycins) and unusual selenium dioxide oxidations of α-alkynyl ethers. Helical acetylenic cyclophanes (Revolvenynes) were synthesized by sequential palladium- and copper-mediated reactions, which set the precedent for later research. Related cyclophanes as potential intermediates for buckminsterfullerene (C60) are discussed. Helical carbocyclic liquid crystalline and heterocyclic (copper-free and complexed) cyclophanes were also prepared. A very strained 153.5° triple bond was discovered which reacted with cyclohexadiene to form the bicyclic adduct in situ and extruded ethylene to generate a new cyclophane with an annulated benzene ring attached. In situ desilylation-dimerization sequences are described and a table is presented for guidance to predict the preferred product from competing intra- and intermolecular copper-mediated coupling pathways. The synthetic details for two different helical, π-stacked C60 cyclophane families with para and meta bonded caps and different structural motifs are presented (Scheme [13] and Scheme [14] ) for comparison with Scheme [1] . These concepts are being extended to the synthesis of allenocyclophanes. A brief discussion of a π-extended boron-azulene complex is followed by a summary of magnesium-mediated carbometallations of propargyl alcohols. A final comment reexamines our cyclophane-based approach to buckminsterfullerene.

  • 1 Acetylene Natural Products (Wyerone, Crepenynic Acid)

  • 2 Enediynes (Taxamycins)

  • 3 Acetylenic Cyclophanes

  • 3.1 Revolvenynes

  • 3.2 Enediynes for C60?

  • 3.3 Carbocycles

  • 3.4 Heterocycles

  • 3.5 C60 Carbocycles

  • 3.6 Termini Separation

  • 4 Allenophanes

  • 5 π-Conjugated Boranes

  • 6 Propargyl Alcohols (Magnesium-Mediated Carbometallations)

  • 7 Buckminsterfullerene (Revisited)

  • 8 Conclusion

1

I have taken Peter at his word and this account is not a comprehensive review but a personal journey through the forest of organic chemistry. I apologize for only passing credit to the chemical literature and the discoveries of others that made our work possible.

4

I later learned that his wife apparently preferred the bustle and bright lights of London to the pastoral scholarly life of Cambridge!

21

Canada has a strategic grant program to support research in collaboration with an industrial partner, provided there is applied potential that will benefit society.

36

Universal Force Field (UFF) calculations were obtained using the Cerius2-Dmol3 molecular modeling suite from Molecular Simulations Inc. San Diego, 1999. We thank S. Drouin and D. Fogg (University of Ottawa) for assistance.

39

Clay, M. D. unpublished results.

48

After submission of this manuscript for review, a current group member volunteered to examine this idea. The Grignard 134 could not be generated from 81 with magnesium turnings, but with Reike® magnesium it acted as a base and the chloride was eliminated to generate the triple bond (Scheme [13] ); consequently, commencing with a halobenzene is more prudent.