η<sup>3</sup>-Allylpalladium Complexes from Medium-Ring Cycloalkenes
作者:Jean-Marie Rosset、Matthew P. Glenn、John D. Cotton、Anthony C. Willis、Colin H. L. Kennard、Karl A. Byriel、Bruce H. Riches、William Kitching
DOI:10.1021/om971132c
日期:1998.5.1
The dimeric eta(3)-allylpalladium chloride complexes formed from various cycloalkenes (C-7-C-13) and some methyl-and tert-butyl-substituted cycle alkenes have be en characterized by H-1 and C-13 NMR spectroscopy and in selected cases by X-ray crystallography. The formation of syn and anti isomers in the larger ring systems is demonstrated, and complexes with a rearranged ring system are formed from tert-butylcyclodecene and tert-butylcyclododecene. The sesquiterpene, carophyllene, is shown to form an eta(3)-allyl exocyclic complex, exclusively from the (E)-double bond. Cis and trans isomers, with respect to allyl group orientation in these halo-bridged dimers, have been identified by low-temperature (190K) NMR spectroscopy, and their interconversion (Delta G(double dagger) approximate to 11 kcal/mol) is considered to involve a "cubic" eta(3)-allylpalladium chloride tetramer.
Amine Oxides. VIII. Medium-sized Cyclic Olefins from Amine Oxides and Quaternary Ammonium Hydroxides<sup>1,2</sup>
作者:Arthur C. Cope、Engelbert Ciganek、Charles F. Howell、Edward E. Schweizer
DOI:10.1021/ja01502a053
日期:1960.9
Thermal decompositions of the N-oxides derived from N,N-dimethyl-1-methylcycloalk,lamines II having eight-, nine- and ten-membered rings yield olefin mixtures containing 98.6, 94.0 and 97.5%, respectively, of 1-methylcycloalkenes. Considerable amounts of the trans isomers are formed from the nine- and ten-membered N-oxides. Pyrolyses of the corresponding quaternary hydroxides produce mixtures of methylenecycloalkanes and 1-methylcycloalkenes (predominantly cis), violation of the Hofmann rule being at a maximum in the decomposition of the nine-membered quaternary hydroxide. Importance of relative product stabilities and the operation of non-bonded interactions are discussed as possible explanations for the observed directions of elimination. Thermal decompositions of the N-oxides and quaternary hydroxides of dimethylcycloalkvimethylamines IV containing eight-, nine- and ten-membered rings proceed as expected with formation of the corresponding methylenecycloalkanes.