The advent of well-defined catalysts for olefin metathesis which combine high activity, durability, and excellent tolerance towards polar functional groups has revolutionized the field. The past decade has seen the rapid embrace of these reagents as tools for advanced organic and polymer chemistry and the success of this development is witnessed by a plethora of elegant applications to the synthesis of natural and nonnatural products. This review article provides an overview of these developments and intends to familiarize the reader with some very recent advances which hold the promise to expand the scope of the reaction even further. Moreover, the positive impact of metathesis on the fundamental logic of retrosynthetic planning is demonstrated by means of typical examples. Finally, it will be shown that metathesis is by no means restricted to alkenes as substrates, and some comments on metathesis reactions following unconventional mechanistic pathways will also be presented.

Olefin Metathesis and Beyond

Poly(aryleneethynylene)s: Syntheses, Properties, Structures, and Applications

The preparation of urea by Wöhler constituted a landmark achievement in organic chemistry, and it laid the ground for the early days of target-oriented organic synthesis.1 Since then, significant progress has been achieved in this discipline; many powerful single bond forming reactions and asymmetric variants have been developed. These discoveries have paved the way for the stereoselective assembly of complex organic molecules, a task deemed inconceivable by early practitioners. A great many strategies were invented by chemists in order to facilitate the synthesis of complex natural products.2 One avenue in emulating nature’s efficiency would * To whom correspondence should be addressed. E-mail: dennis.hall@ ualberta.ca. † Novartis Institute for Biomedical Research. ‡ Department of Chemistry, University of Alberta. Chem. Rev. 2009, 109, 4439–4486 4439

Natural product synthesis using multicomponent reaction strategies.

Department of Chemistry, William Mong Institute of Nano Science and Technology, Bioengineering Graduate Program, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong, China, and Department of Polymer Science and Engineering, Key Laboratory of Macromolecular Synthesis and Functionalization of the Ministry of Education, Institute of Biomedical Macromolecules, Zhejiang University, Hangzhou 310027, China

Acetylenic polymers: syntheses, structures, and functions.

With the exception of palladium-catalyzed cross-couplings, no other group of reactions has had such a profound impact on the formation of carbon-carbon bonds and the art of total synthesis in the last quarter of a century than the metathesis reactions of olefins, enynes, and alkynes. Herein, we highlight a number of selected examples of total syntheses in which such processes played a crucial role and which imparted to these endeavors certain elements of novelty, elegance, and efficiency. Judging from their short but impressive history, the influence of these reactions in chemical synthesis is destined to increase.

Metathesis Reactions in Total Synthesis

Tungsten(VI) neopentylidyne complexes

Etude structurale des composes Ti 2 (OPr i ) 4 [(O-CHCONHCH 2 Ph) 2 ] 2 et Ti 2 (OEt) 2 (O−NPh−C(O)Ph) 2 [(O−CH−CO 2 −Et) 2 ] 2

Crystal structures of two titanium tartrate asymmetric epoxidation catalysts

Das Tetrachloroalkylidinwolframat (I) reagiert mit Alkinen zu Produkten, fur die aufgrund einer Rontgenstrukturanalyse des Methyl-Derivats (RG P21/c, Z=4) die Cyclopentadienylalkin-Struktur (III) bestatigt wird.

Reaction of tungsten(VI) alkylidyne complexes with acetylenes to give tungstenacyclobutadiene and cyclopentadienyl complexes

Chiral recognition in the synthesis of dimetalla-4-tert-butylcalix[8]arene complexes. The incorporation of a metal-alkoxide ligand into a molecular cavity

Steven F. Pedersen

Papers

Tungsten(VI) neopentylidyne complexes

Crystal structures of two titanium tartrate asymmetric epoxidation catalysts

Reaction of tungsten(VI) alkylidyne complexes with acetylenes to give tungstenacyclobutadiene and cyclopentadienyl complexes

Chiral recognition in the synthesis of dimetalla-4-tert-butylcalix[8]arene complexes. The incorporation of a metal-alkoxide ligand into a molecular cavity

Unexpected diversity in the coordination chemistry of tartrate esters with titanium(IV)