title: A Raney-cobalt-mediated tandem reductive cyclization route to the 1,5-methanoazocino[4,3-b]indole framework of the uleine and Strychnos alkaloids.
abstract: The readily accessible enones 8, 17, and 18 undergo 2-fold reductive cyclization reactions upon exposure to hydrogen in the presence of Raney-cobalt and thereby afford compounds 11 (72%), 19 (47%), and 20 (84%), respectively. These products embody the ABCD-ring system associated with the title alkaloids, and compound 11 can be converted, over four steps and in 33% yield, into congener 24 incorporating the ABCDE-ring system of the Strychnos alkaloids.
authors.affiliation: Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra ACT 0200, Australia.
authors.forename: Tristan A
authors.initials: TA
authors.lastname: Reekie
authors.forename: Martin G
authors.initials: MG
authors.lastname: Banwell
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Willis
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D001392:Azocines / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D031451:Strychnos / Q000737:chemistry*
chemical_list: C581627:1,5-methanoazocino(4,3-b)indole; D000470:Alkaloids; D001392:Azocines; D001952:Bridged-Ring Compounds; D007211:Indoles; C428545:uleine; D003035:Cobalt