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Synlett 2012(2): 185-207  
DOI: 10.1055/s-0031-1290120
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

‘Pseudo-halide’ Derivatives of Grubbs- and Schrock-Type Catalysts for Olefin Metathesis

Emily Baird Andersona, Michael R. Buchmeiser*a,b
a Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Institut für Polymerchemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
b Institut für Textilchemie und Chemiefasern (ITCF), Körschtalstr. 26, 73770 Denkendorf, Germany
Fax: +49(711)68564050; Fax: +49(711)9340185; e-Mail: michael.buchmeiser@ipoc.uni-stuttgart.de;
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Publikationsverlauf

Received 11 July 2011
Publikationsdatum:
22. Dezember 2011 (online)

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Abstract

Metathesis has persisted through the years as a formidable synthetic approach to various unsaturated organic molecules and macromolecules. The 21st century developments in olefin metathesis continue to feature more efficient and selective, well-defined metathesis catalysts. Due to the easily regulated steric and electronic properties of ‘pseudo-halide’ derivatives, their study has launched a new milestone in ruthenium- and molybdenum-based catalysis. Synthesizing ‘pseudo-halide’ derivatives often entails replacing halide ligands with easily modified carboxylates, perfluorocarboxylates, phenoxides, isocyanates, isothiocyanates, pyridines, nitrates, and trifluoromethanesulfonates. This account elucidates the recent advances in ‘pseudo-halide’-containing olefin metathesis, including synthetic approaches to obtain new catalysts and optimization of the ligand sphere. Several innovations in Ru- and Mo-alkylidenes that concern initiation efficiency, reactivity, stereoselectivity, supported catalysis, cyclopolymerization, and copolymerization are described. Refinement of the anionic ‘pseudo-halide’ ligands has enabled the perfection of Ru- and Mo-based metathesis catalysts in both reactivity and selectivity. These advances have led to stereoselectivity in polymerizations, improved copolymerization affinity, and the regioselective cyclopolymerization of 1,6-heptadiynes to result in conjugated polymers solely based on five-membered repeat units.

1 Introduction

2 Catalyst Synthesis

2.1 Modified Ru-Alkylidene-Based Metathesis Catalysts

2.1.1 Halides, Alkoxides, and Aryloxides

2.1.2 Bidentate or Monodentate Carboxylates

2.1.3 Nitrates and Trifluoromethanesulfonates

2.1.4 Isocyanates and Isothiocyanates

2.2 Modified Mo-Alkylidene-Based Metathesis Catalysts

2.2.1 Bidentate or Monodentate Carboxylates

2.3 Supported Catalysts

3 Characterization and Structural Effects

3.1 General Procedures

3.2 X-ray Structures

3.3 ¹H and ¹³C NMR Shifts of the Alkylidene Resonances

4 Catalysis in Organic Synthesis

4.1 Ring-Closing Metathesis (RCM)

4.2 Other Metathesis Reactions

5 Catalysis in Polymerization

5.1 Ring-Opening Metathesis Polymerization (ROMP)

5.1.1 2-Norbornene (NBE)

5.1.2 Cyclooctene (COE)

5.1.3 cis-1,5-Cyclooctadiene (COD)

5.2 Cyclopolymerization of 1,6-Heptadiynes

5.2.1 Diethyl Dipropargylmalonate (DEDPM)

5.2.2 Other 1,6-Heptadiynes

5.3 Copolymerization

5.3.1 Copolymers via Ring-Opening Metathesis Polymerization (ROMP)

5.3.2 Copolymers of 1,6-Heptadiynes with Acetylene

6 Summary and Outlook

Key words

alkylidenes - olefin metathesis - catalysis - ruthenium - molybdenum - ring-closing metathesis - ring-opening metathesis polymerization - cyclopolymerization - 1,6-heptadiynes