Palladium-catalyzed cross-coupling reactions and electrocyclizations - Efficient combinations for new cascade reactions

Armin de Meijere*, Michael Schelper, Mario Knoke, Baris Yucel, Hans Wolf Sünnemann, René Peter Scheurich, Lars Arve

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Palladium-catalyzed cross-coupling reactions and electrocyclic transformations as well as cycloadditions can efficiently be combined in one-pot sequences to build up complex molecules from simple precursors. 1,3-Dicyclopropyl-1,2-propadiene (1) could be coupled to various aryl halides, and the 1,3,5-hexatrienes resulting after rearrangement were trapped with different dienophiles. Further exploration of the highly reactive building block bicyclopropylidene (8) demonstrates the combinatorial potential of the two reaction modes in terms of two different three-component reactions, and even a novel four-component reaction was readily developed. Additional increase of complexity was gained by combining an intramolecular Heck reaction with consecutive trapping by 8, which can be carried out with or without 6π-electrocyclization. Finally a Stille-Heck-coupling sequence of substituted 2-bromocycloalkenyl triflates with functionally substituted alkenylstannanes and acrylic esters led to highly substituted 1,3,5-hexatrienes, which smoothly underwent 6π-electrocyclization at elevated temperatures to yield bi- and tricyclic skeletons. With this methodology at hand, a new versatile access to steroid-analogues with a diene moiety in the B ring and a functionality at C-7 was developed.

Original languageEnglish
Pages (from-to)249-255
Number of pages7
JournalJournal of Organometallic Chemistry
Volume687
Issue number2
DOIs
Publication statusPublished - 7 Dec 2003
Externally publishedYes

Funding

This work was supported by the Studienstiftung des Deutschen Volkes and the Fonds der Chemischen Industrie as well as Bayer, BASF, Degussa AG and Chemetall GmbH through generous gifts of chemicals. A. de M. is indebted to a large group of dedicated and enthusiastic young chemists who have carried out the described research. The authors are grateful to Dr. Burkhard Knieriem for his careful proofreading of the final manuscript.

FundersFunder number
Degussa AG
Bayer
BASF
Verband der Chemischen Industrie
Studienstiftung des Deutschen Volkes
Chemetall

    Keywords

    • Cascade reactions
    • Combinatorial chemistry
    • Cross coupling
    • Palladium catalysis
    • Small rings

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