2005
Ring closure reactions
O 0130
Broensted Acid Catalyzed Highly Stereoselective Arene-Ynamide Cyclizations. A
Keteniminium Pictet—Spengler Cyclization in Total Syntheses of (±)-Des32- 052 Novel
bromoarborescidines A and C. — The title reaction is described for a variety of arene-ynamides and is also for the first time, in the total synthesis of the alkaloids (XX)
and (XXI). PtCl4, HNTf2 and p-nitrosulfonic acid are shown to be most effective catalysts. — (ZHANG, Y.; HSUNG*, R. P.; ZHANG, X.; HUANG, J.; SLAFER, B. W.;
DAVIS, A.; Org. Lett. 7 (2005) 6, 1047-1050; Dep. Chem., Univ. Minn., Minneapolis,
MN 55455, USA; Eng.) — R. Steudel
2005