TETRAHEDRON, cilt.65, sa.1, ss.115-118, 2009 (SCI-Expanded)
In this study, a new synthetic route for the total synthesis of (+/-)-uleine is described. The important step in the synthesis of this alkaloid consists of an intramolecular cyclization of the D ring of the azocino[4, 3-b]indole skeleton. Reduction of (N-methyl){3-beta-ethyl-4-oxo-2,3,4,9-tetrahydrospiro[1H-carbazole-1,2'(1,3)dithiolane]-2-yl}-2-acetamide with borane yielded the corresponding (N-methyl){3-beta-ethyl-4-hydroxy-2,3,4,9-tetrahydrospiro[1H-carbazole-1,2'(1,3)dithiolane]-2-yl}-2-acetamide, which underwent acid-catalyzed ring closure to produce azocino[4,3-b]indole core. Finally, the synthesis of (+/-)-uleine was completed through several steps from the azocino[4,3-b]indole core. (C) 2008 Elsevier Ltd. All rights reserved.