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Synlett 2006(18): 2861-2878  
DOI: 10.1055/s-2006-951527
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

Interplays between Reactions within and without the Catalytic Cycle of the Heck Reaction as a Clue to the Optimization of the Synthetic Protocol

Alexander F. Schmidt*a, Ayman Al Halaiqaa, Vladimir V. Smirnovb
a Department of Chemistry of Irkutsk State University, 1 K. Marx Str., 664003, Irkutsk, Russia
b Department of Chemical Engineering and Metallurgy of Irkutsk State Technical University, 83 Lermontov Str., 664074, Irkutsk, Russia
Fax: +7(3952)421935; e-Mail: aschmidt@chem.isu.ru;
Further Information

Publication History

Received 7 April 2006
Publication Date:
25 October 2006 (online)

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Abstract

This account presents previous and recent mechanistic studies of the Heck reactions reported by the authors whose attention has been focused on a problem of the coupling of catalyst transformations within and without the catalytic cycle. Based on the understanding of the interaction mechanism between these processes a development of new methods of Heck chemistry became conceivable. In particular, such a rational approach allowed an elaboration of the ligand-free systems, which are effective not only in the reaction with non-activated aryl bromides but also with non-activated aryl chlorides.

  • 1 Introduction

  • 2 Main Catalytic Cycle

  • 2.1 Pd(0)/Pd(II) Catalytic Cycle

  • 2.2 Rate-Limiting Step of the Main Catalytic Cycle in the Heck Reaction with Aryl Iodides

  • 3 Reactions without the Main Catalytic Cycle of the Heck Reaction

  • 3.1 Reduction of Palladium

  • 3.2 Oxidation of Palladium

  • 3.3 Agglomeration of Palladium

  • 3.4 Dissolution of Palladium

  • 3.5 Dissolution of Palladium as a Rate-Limiting Step of the Heck Reaction with Aryl Bromides

  • 4 Coupling Effects of the Catalyst Reactions within and without the Main Catalytic Cycle

  • 4.1 Reaction with Aryl Iodides

  • 4.2 Reaction with Aryl Bromides and Aryl Chlorides

  • 4.3 Reaction with the Heterogeneous Catalyst Precursors

  • 5 Conclusions and Outlook

Key words

Heck reaction - catalysis - palladium - coupling mechanism - rate-limiting step

71

Schmidt, A. F. Three-Experiment Method for the Elucidation of the Rate-Limiting Step in Catalytic Reactions. Theoretical Considerations, article is available online under http://www.chem.isu.ru or from the author.

72

Newton and Conjugated Gradient methods (Microsoft Excel 2002) were used.

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The coordination of alkene should be this step. But because of its reversibility the following step of alkene insertion to Pd-C bond may also influence the value of L.

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Schmidt, A. F.; Smirnov, V. V.; Köhler, K., unpublished results.