Open AccessAn Unexpected Tandem Reaction between N-Butadienyl-N-alkylketene N,O-Trimethylsilylacetals of Propionamide and Activated Dienophiles like N-Phenyl-maleimide or Acryloyl Chloride
Author(s) -
Marcel Baak,
Yves Rubin,
Andreas H. Franz,
Helen Stœckli-Evans,
Laurant Bigler,
Jiirgen Nachbauer,
Reinhard Neier
Publication year - 1993
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.1993.233
Subject(s) - acryloyl chloride , bicyclic molecule , maleimide , acylation , yield (engineering) , chemistry , imide , chloride , bridged compounds , medicinal chemistry , diels–alder reaction , acyl chloride , benzoyl chloride , stereochemistry , organic chemistry , catalysis , materials science , acrylate , monomer , metallurgy , polymer
Starting from the N-butadienyl-N-alkylpropionamides 1a-1c the corresponding N,O-trimethylsilylacetals could be obtained using the mixture of LDA and trimethylsilyl chloride in THF. The unexpected reaction sequence Diels-Alder reaction/acylation between the N-butadienyl-N-alkylketene N,O-trimethylsilylacetal of propionamide (2a-2b) and N-phenylmaleimide produced tricyclic products rac-5a-rac-5b and bicyclic products rac-6a–rac-6b with high diastereoselectivity. The reaction of the N,O-trimethylsilylacetals 2a and 2c with acryloyl chloride in a similar sequence gave the bicyclic products rac-8a and rac-8c. The stepwise synthesis of bicyclic systems of this general structure could only be successfully executed in 26% yield treating the Diels-Alder product rac-10 with LDA.