A concise, asymmetric synthesis of the indole alkaloid (+)-tacamonine is reported involving a stereoselective radical cyclization of a 1-phenylsulfanyl tetrahydro-β-carboline bearing a pendant enoate ester side chain as a key step. In this process, a single stereocenter in the side chain allows for the formation of two stereocenters of the natural product in a highly diastereoselective fashion. Computational investigations of this key cyclization support the experimentally observed outcome and shed light on the factors impacting its stereoselectivity.
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