Gold catalysis in stereoselective natural product synthesis: (+)-linalool oxide, (-)- isocyclocapitelline, and (-)-isochrysotricine

A stereoselective synthesis of the tetrahydrofuran-containing natural products (2S,5R)-(+)-linalool oxide (1), (-)-isocyclocapitelline (2), and (-)-isochrysotricine (3) is reported. Key steps are the copper-mediated S(N)2'-substitution of propargyl oxiranes 7 and the gold-catalyzed cycloisomerization of dihydroxyallenes 8/17, resulting in a highly efficient center-to-axis-to-center chirality transfer. The enantioselective total synthesis of (-)-isocyclocapitelline (2) and (-)-isochrysotricine (3) allowed the elucidation of the absolute configuration of these beta-carboline natural products. (C) 2008 Elsevier Ltd. All rights reserved.