Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

• Published in: Nature (London) 2017-02, Vol.542 (7639), p.80-85
• Main Authors: Koh, Ming Joo, Nguyen, Thach T., Lam, Jonathan K., Torker, Sebastian, Hyvl, Jakub, Schrock, Richard R., Hoveyda, Amir H.
• Format: Article
• Language: English
• Subjects: 639/638/403/977; 639/638/77; Alkenes; Alkenes - chemical synthesis; Alkenes - chemistry; Catalysis; Catalysts; Chemical properties; Chemical reactions; Chloride; Chlorides; Chlorides - chemistry; Fluorocarbons - chemistry; Humanities and Social Sciences; letter; Ligands; Methods; Molybdenum; Molybdenum - chemistry; Molybdenum compounds; multidisciplinary; Ruthenium; Science; Tungsten
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature21043

Substitution of a ligand in molybdenum-based complexes enables typically inert hexafluorobutene to participate in Z -selective olefin cross-metathesis reactions. Olefin metathesis that favours Z isomers Catalytic olefin metathesis, which was recognized with a Nobel Prize in 2005, is used in the synthesis of molecules ranging from drugs to agrochemicals. Many advances have been made to gain control over which isomers are formed in these reactions, and what precursors can be reacted. Now Amir Hoveyda and colleagues show that with careful tuning of the ligands of molybdenum-based complexes, inert hexafluorobutene, which has never previously been seen to participate in any chemical transformation, can be persuaded to participate in metathesis reactions. This provides a new route to making trifluoroalkenes, and is surprisingly highly selective for the Z isomer. The development of catalyst-controlled stereoselective olefin metathesis processes 1 has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum 2 , tungsten 3 and ruthenium 4 has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy ( Z ) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z -1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z- 1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles 5 , are elucidated with the aid of density functional theory calculations.