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Unexpected Heterocyclic Products from Cycloaddition Reactions of Nonsymmetrical Allenyl Aldoketazines with Substituted Alkynes
Author(s) -
Galeta Juraj,
Man Stanislav,
Bouillon JeanPhilippe,
Potáček Milan
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001044
Subject(s) - cycloaddition , chemistry , ring (chemistry) , trifluoromethyl , crystal structure , reaction conditions , combinatorial chemistry , medicinal chemistry , stereochemistry , organic chemistry , catalysis , alkyl
Thermally initiated cycloaddition reactions of nonsymmetrical allenyl azines 1 with alkynes or other dipolarophiles usually lead to compounds with three fused, five‐membered heterocyclic rings. With alkynes with pronounced “push–pull” systems, however, the reaction ends with the formation of substituted pyrrolidino[1,2‐ b ]pyrazoles 4 and, in the case of azines with trifluoromethyl substitution, ring opening leads to the isolation of compounds 9 . Reaction mechanisms for these transformations are proposed. The molecular structures of the new heterocycles 4 and 9 were confirmed by X‐ray crystal structure analysis.