Iron Tricarbonyl Stabilized Pentadienyl Cation as Initiator for Cascade Polycyclizations:  A Diastereoselective Entry into Octahydrophenanthrenes

• Published in: Journal of organic chemistry Vol. 69; no. 25; pp. 8975 - 8978
• Main Authors: Pearson, Anthony J, Ghidu, Victor P
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 10.12.2004; Amer Chemical Soc
• Subjects: Chemical reactivity; Chemistry; Chemistry, Organic; Exact sciences and technology; Organic chemistry; Physical Sciences; Reactivity and mechanisms; Science & Technology; CHEMISTRY; DIENE COMPLEXES; BIOMIMETIC POLYENE CYCLIZATIONS; Phenanthrene derivatives; Catalytic reaction; Catalyst selectivity; Transition metal Carbonyl Complexes; Complex catalyst; Experimental study; Regiospecificity; Diastereoselectivity; Iron Carbonyl Complexes; Cyclization; Polyenic compound; Catalyst activity; Successive reaction
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo048557a

A new example is provided of completely diastereoselective polycyclization, affording the octahydrophenanthrene framework. Generation of an iron tricarbonyl stabilized pentadienyl carbocation is the triggering event of the cascade reaction. The carbocation is generated by anchimerically assisted regiospecific protonation of a double bond adjacent to the iron tricarbonyl diene moiety. Tetrafluoroboric acid ether complex appears to be the optimum reagent, affording good yields, even under catalytic conditions.