N -Acyliminium ion chemistry and palladium catalysis: a useful combination to obtain bicyclic heterocycles
摘要:
By using N-acyliminium ion chemistry, several omega -propadienyllactams and a propadienyloxazolidine were prepared from N-acyliminium ion precursors and propargylsilanes. Treatment of these allene containing lactams and oxazolidinone with allyl halides or an allyl carbonate using Pd(II)-salts as the catalyst gave rise to a coupling-cyclization reaction, yielding bicyclic systems in which the allyl moiety is incorporated. With this methodology several substituted pyrrolizinones, an oxazolone and indolizinone were prepared. (C) 2001 Elsevier Science Ltd. All rights reserved.
By using N-acyliminium ion chemistry, several omega -propadienyllactams and a propadienyloxazolidine were prepared from N-acyliminium ion precursors and propargylsilanes. Treatment of these allene containing lactams and oxazolidinone with allyl halides or an allyl carbonate using Pd(II)-salts as the catalyst gave rise to a coupling-cyclization reaction, yielding bicyclic systems in which the allyl moiety is incorporated. With this methodology several substituted pyrrolizinones, an oxazolone and indolizinone were prepared. (C) 2001 Elsevier Science Ltd. All rights reserved.
Expedient Pyrrolizidine Synthesis by Propargylsilane Addition to<i>N</i>-Acyliminium Ions followed by Gold-Catalyzed α-Allenyl Amide Cyclization
作者:Arjen C. Breman、Jan Dijkink、Jan H. van Maarseveen、Sape S. Kinderman、Henk Hiemstra
DOI:10.1021/jo901393y
日期:2009.8.21
A reaction sequence, involving the addition of (substituted) propargylsilanes to lactam-derived N-acyliminiumions followed by gold-catalyzed cyclization of the resulting α-allenyl amide, is applied in expedient syntheses of pyrrolizidinealkaloids heliotridine and ent-retronecine in five steps from (S)-malic acid.