First total synthesis of (+/-)-stemonamide and (+/-)-isostemonamide.
[structure: see text] The total synthesis of the tetracyclic alkaloids stemonamide (1) and isostemonamide (2) is presented. The key step is the reaction between a silyloxyfuran and an N-acyliminium ion. The second quaternary center is created by an intramolecular aldol spirocyclization. After 1,4-addition of an appropriate side chain, the methyl and double bond are installed by Mannich reaction. The seven-membered ring is closed by intramolecular nucleophilic displacement.
Kende
A S
AS
Department of Chemistry, University of Rochester, Rochester, NY 14627, USA. kende@chem.rochester.edu
Hernando
J I
JI
Milbank
J B
JB
D000470:Alkaloids / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D003500:Cyclization; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D018517:Plant Roots / Q000737:chemistry; D010944:Plants / Q000737:chemistry*; D011083:Polycyclic Compounds / Q000138:chemical synthesis*; D013055:Spectrophotometry, Infrared; D013141:Spiro Compounds / Q000138:chemical synthesis*
D000470:Alkaloids; D007202:Indicators and Reagents; D011083:Polycyclic Compounds; D013141:Spiro Compounds; C434309:stemonamide