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Push‐pull‐Cyclobutadiene
Author(s) -
Neuenschwander M.,
Niederhauser A.
Publication year - 1970
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.19700530308
Subject(s) - chemistry , electrophile , cyclobutadiene , nucleophile , cleavage (geology) , push pull , medicinal chemistry , cyanine , stereochemistry , organic chemistry , molecule , catalysis , fluorescence , physics , geotechnical engineering , electrical engineering , quantum mechanics , fracture (geology) , engineering
Two push‐pull‐cyclobutadienes 10b and 10c are prepared by reaction of two eq. of the corresponding acetylenes having electrondonating and electronaccepting groups ( 4 ) with one eq. of HBF 4 to cyclic cyanine salts, followed by elimination of HBF 4 with KOC(CH 3 ) 3 . These cyclobutadienes, stable in cristalline form at room temperature respectively for a short time ( 10b RCH 3 ) or for several days ( 10c ROCH 3 ), are extremely reactive in solution towards various nucleophiles and electrophiles. Cleavage of the nascent cyclobutenes leads to butadienes. The cyclobutadienes 10 dimerise thermally to cyclooctatetraenes 18 .