Synlett 2011(11): 1495-1514  
DOI: 10.1055/s-0030-1260579
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Highly Substituted Indoles via Diels-Alder/Plieninger Indolization Sequence: Applications in Total Synthesis

Katarina Sapeta, Terry P. Lebold, Michael A. Kerr*
Department of Chemistry, The University of Western Ontario, London, ON, N6A 5B7, Canada
Fax: +1(510)6613022; e-Mail: makerr@uwo.ca;
Further Information

Publication History

Received 18 February 2011
Publication Date:
26 May 2011 (online)

Abstract

This account describes the development of a Diels-­Alder-based methodology towards highly functionalized dihydronaphthalenamines, and their conversion into indoles through a modified Plieninger procedure. Applications towards the total synthesis of indole-containing natural products will be presented.

1 Introduction

2 Synthesis of Indoles via Diels-Alder Cycloadditions/­Plieninger Indolization

2.1 High Pressure Diels-Alder Cycloadditions of Quinone ­Imine Ketals (QIKs)

2.2 Thermal Diels-Alder Cycloadditions of QIKs

2.3 Development of a Modified Plieninger Protocol

2.4 Diels-Alder Cycloadditions/Indolization of p-Benzoquin­one Monoimines

3 Applications to Natural Products Synthesis

3.1 Ergot Alkaloids: Chanoclavine I (Plieninger)

3.2 Rivularins (Maehr)

3.3 Polyalkylated Indoles: Herbindoles and Trikentrins (Kerr)

3.4 Tremorgenic Indole Terpenoids: Lolicine Western Hemisphere (Kerr)

3.5 Antitumor Agents: Yatakemycin (Boger) and CC-1065 (Kraus, Kerr)

3.6 Antimalarials: Decursivine (Kerr)

3.7 Carbazole Natural Products: The Clausamines and Eustifolines (Kerr)

4 Summary and Outlook

13

Although not isolated in practice, the crude diol and dicarbonyl species were characterized in one case to confirm that these were, in fact, synthetic intermediates.