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Cycloadditions of Bifunctional Vinyl Ethers with Electrophilic Alkenes through Tetramethylene Zwitterion Intermediates
Author(s) -
May Eric J.,
Padias Anne Buyle,
Bates Robert B.,
Hall Henry K.
Publication year - 2005
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200590112
Subject(s) - zwitterion , chemistry , cyclobutanes , bifunctional , steric effects , cyclobutane , electrophile , tetracyanoethylene , photochemistry , medicinal chemistry , organic chemistry , polymer chemistry , catalysis , molecule , ring (chemistry)
Bifunctional vinyl ethers react with electron‐poor alkenes to cyclobutanes in good yields. The second CC bond reacted with neither the cyclobutane nor its zwitterion intermediate, even on heating. Cyclobutanes formed from ‘tetracyanoethylene’ ( 8 ) were transformed into tetrahydropyridines by reaction of the corresponding zwitterion with MeCN as the solvent. In contrast, cyclobutanes formed from dimethyl (dicyanomethylidene)propanedioate ( 9 ) did not react with MeCN, which is ascribed to diminished stabilization of the zwitterion intermediate, and increased steric effects. These results extend the classical studies of Huisgen and his co‐workers.