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2.10.2.2.2.2 Z-Selective Ring-Closing Metathesis

DOI: 10.1055/sos-SD-222-00346

Lee, D.; Reddy Sabbasani, V.Science of Synthesis: Metal-Catalyzed Cyclization Reactions, (20162551.

The selective formation of Z-alkenes by metathesis has been a long-standing challenge because of the inherently equilibrating nature of the alkene metathesis mechanism. Thus, the formation of macrocycles via ring-closing metathesis in a substrate-controlled manner generally displays low E/Z selectivity and also frequently low yields mainly because of an entropic disadvantage. However, on some occasions, although not predictable, high Z selectivity can be realized in macrocyclic ring-closing metathesis. This is probably the result of a convoluted influence of the existing functional groups and their stereochemical array in combination with a particular ring size. To address this problem, catalyst-based E/Z selectivity control would be highly desirable, for which development of catalyst systems is crucial.

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