title: Free-radical approaches to stemoamide and analogues.
abstract: Two approaches allowing access to the tricyclic stemona backbone are presented. Both approaches rely on a free-radical cyclization reaction as the key step. In the formal synthesis of (+/-)-stemoamide, the construction of the A ring of the natural product was achieved via a 5-exo-trig radical cyclization with atom transfer. The two diastereoisomers issuing from this cyclization showed different reactivity while forming the seven-membered ring of the final product. In the second part of this study, a 7-exo-trig free radical cyclization was realized allowing access to the (+/-)-9,10-bis-epi-stemoamide. This reaction was highly stereoselective and allowed the control of three of the four contiguous stereocenters present in the molecule.
authors.affiliation: Laboratoire de Chimie Organique, associé au CNRS, ESPCI, 10 rue Vauquelin, 75231, Paris Cedex 05, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bogliotti
authors.forename: Peter I
authors.initials: PI
authors.lastname: Dalko
authors.forename: Janine
authors.initials: J
authors.lastname: Cossy
mesh_terms: D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry*; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013055:Spectrophotometry, Infrared
chemical_list: D005609:Free Radicals; D006575:Heterocyclic Compounds, 3-Ring; D007783:Lactones; C519217:stemoamide