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Please login to access the full content or check if you have access via Method 1: Ring Closure by Alkynylmetal Condensations with Carbonyl Groups and Related Electrophiles

DOI: 10.1055/sos-SD-043-00217

Fallis, A. G.; Souweha, M. S.Science of Synthesis, (200843293.

Acetylenes are one of the first functional groups that chemists encounter in their early education. We also learn about the acidity of the acetylenic hydrogen and the ease with which it can be converted into Grignard reagents and related nucleophilic species. Consequently, the disconnection of an α-hydroxyethynyl functionality to allow intramolecular ring formation from the condensation of a lithium, potassium, or a related alkynyl anion with a carbonyl group or related electrophile is an obvious retrosynthetic step.[‌22‌] Scheme 7 illustrates an example, the transformation of aldehyde 8 to cyclononenyne 9.[‌23‌,‌24‌] Alkynyl anion manipulation is also a common method of ring closure for substituted cyclononenynes and the higher C10C12 homologues (see Sections,, and Despite the simplicity of anion generation, there are many instances where this reaction fails and other solutions have evolved.

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