Synthese von Heterocyclen durch C-C-Knüpfung. II. Katalytische Cyclisierung von N-Alkyl-N-allyl-acrylamiden und N.N-Diallyl-carbonsäureamiden

Synthesis of Heterocycles by C C-Bond Formation. II. Catalytic Cyclization of N-Alkyl-N-allyl-acrylamides and N,N-Diallyl Carbonic Acid Amides N-Alkyl-N-allyl-acrylamides 2 cyclize in the presence of PdCl₂ to 1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones 4 and 1-alkyl-4-methyl-3-methylene-pyrrolidin-2-ones 5 . Compounds 4 predominate in the mixture. With RhCl₃, ring closure gives comparable amounts of lactams 4 and 7 (1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones) besides some product of allyl elimination. N. N-Diallyl carboxylic amides 3 form cyclic enamides (1-acyl-3,4-dimethyl-2-pyrrolines, 9 ) on the action of PdCl₂ besides the products 10 of allyl elimination. RhCl₃ effects cyclization of 3 to form 1-acyl-3-methyl-4-methylene-pyrrolidines 11 besides some 9 . The acid amide groups of compounds 9 and 11 are shown by n.m.r. spectroscopy to exist as rotamers.