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Cäsium‐Effekt bei C–C‐Bindungsknüpfungen zu vielgliedrigen Kohlenwasserstoff‐Ringen
Author(s) -
Vögtle Fritz,
Kißener Wolfram
Publication year - 1984
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19841170726
Subject(s) - chemistry , alkali metal , caesium , oligomer , potassium , sodium , benzene , metal , hydrocarbon , medicinal chemistry , polymer chemistry , ring (chemistry) , inorganic chemistry , organic chemistry
Cesium Effect in C–C ‐Bond Forming Reactions Yielding Large Hydrocarbon Rings C–C ‐bond formations of the Wurtz type following the Müller‐Röscheisen procedure [alkali metal + tetraphenylethene (TPE)] leading to [2 n ]paracyclophane rings 2 have been carried out, comparing sodium, potassium, and cesium as metals. As fig. 1 shows, the selectivity of the oligomer formation starting from 1,4‐bis(chloromethyl)benzene ( 1a ) is strongly dependent on the alkali metal used. Sodium/TPE besides 2b predominantly yields the higher oligomers 2c – e . Use of cesium metal/TPE leads to 2b preferentially. With potassium metal/TPE all oligomers 2b – e are obtained in low yields or traces, respectively. According to these results, the oligomer formation in carbocyclic ring systems can be steered by the type of alkali metal applied; cesium seems to favour the formation of conformationally more rigid rings (like 2b ).