Attempts to Mimic Key Bond-Forming Events Associated with the Proposed Biogenesis of the Pentacyclic Lamellarins

Lorraine C. Axford; Kate E. Holden; Katrin Hasse; Martin G. Banwell; Wolfgang Steglich; Jörg Wagler; Anthony C. Willis

doi:10.1071/CH07402

RESEARCH ARTICLE

Attempts to Mimic Key Bond-Forming Events Associated with the Proposed Biogenesis of the Pentacyclic Lamellarins

Lorraine C. Axford ^A , Kate E. Holden ^A , Katrin Hasse ^A , Martin G. Banwell ^A ^C , Wolfgang Steglich ^B , Jörg Wagler ^A and Anthony C. Willis ^A

+ Author Affiliations

- Author Affiliations

^A Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra, ACT 0200, Australia.

^B Department Chemie, Ludwig-Maximilians-Universität, Butenandtstr. 5-13 (Haus F), 81377 München, Germany.

^C Corresponding author. Email: mgb@rsc.anu.edu.au

Australian Journal of Chemistry 61(2) 80-93 https://doi.org/10.1071/CH07402
Submitted: 21 November 2007 Accepted: 3 January 2008 Published: 11 February 2008

Abstract

The pyrrole-tethered veratroles 16 and 27 each engage in PIFA-induced oxidative cyclization reactions to give compounds 22 and 29, respectively, which incorporate a key tricyclic fragment associated with the title natural products. In contrast, the corresponding catechols 11 and 12 only produce polymeric materials on subjection to analogous reaction conditions. Efforts to study lactone ring formation by the oxidative cyclization of catechol 30 and veratrole 38 have been thwarted by an inability to prepare the former substrate and decomposition of the latter. The reported conversions 44 → 45 and 46 → 47 suggest that a C2-carboxy group attached to the pyrrole ring can ‘direct’ the oxidative cyclization of N-tethered aryl groups. The acquisition of compound 22 by the means described herein provides an adventitious and concise route to the racemic modification of the pyrrolo[2,1-a]isoquinoline alkaloid crispine A (52).

Acknowledgements

We thank the Institute of Advanced Studies and the Australian Research Council for generous financial support and the Gottlieb Daimler und Karl Benz-Stiftung for the provision of a scholarship to K.H. J.W. is the grateful recipient of a DAAD-supported postdoctoral fellowship.

References

^* The X-ray crystal structure of the picrate salt of (+)-crispine A has been reported previously – see ref. [37b].

Attempts to Mimic Key Bond-Forming Events Associated with the Proposed Biogenesis of the Pentacyclic Lamellarins

Abstract

Acknowledgements

Subscriber Login