IMDA-radical cyclization approach to (+)-himbacine.
[reaction: see text] A formal total synthesis of the selective muscarinic receptor antagonist himbacine is presented. Key C-C bond-forming steps include an intramolecular Diels-Alder reaction, Stille coupling reactions, and a 6-exo-trig acyl radical cyclization to a conjugated enyne. An unexpected secondary alcohol to chloride conversion is witnessed during attempted thionocarbonate formation.
D000470:Alkaloids / Q000138:chemical synthesis*; D000480:Alkynes / Q000737:chemistry; D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry; D005663:Furans; D009281:Naphthalenes; D010880:Piperidines; D010946:Plants, Medicinal / Q000737:chemistry; D014197:Trees
D000470:Alkaloids; D000480:Alkynes; D005609:Free Radicals; D005663:Furans; D009281:Naphthalenes; D010880:Piperidines; C048172:himbacine