Expedient pyrrolizidine synthesis by propargylsilane addition to N-acyliminium ions followed by gold-catalyzed alpha-allenyl amide cyclization.
A reaction sequence, involving the addition of (substituted) propargylsilanes to lactam-derived N-acyliminium ions followed by gold-catalyzed cyclization of the resulting alpha-allenyl amide, is applied in expedient syntheses of pyrrolizidine alkaloids heliotridine and ent-retronecine in five steps from (S)-malic acid.
Breman
Arjen C
AC
Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS Amsterdam, The Netherlands.
Dijkink
Jan
J
van Maarseveen
Jan H
JH
Kinderman
Sape S
SS
Hiemstra
Henk
H
D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006046:Gold / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D007700:Kinetics; D007769:Lactams / Q000737:chemistry; D011763:Pyrrolizidine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*
D000577:Amides; D007097:Imines; D007769:Lactams; D011763:Pyrrolizidine Alkaloids; D012821:Silanes; D006046:Gold