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Norbornadiene
About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.
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TL;DR: In this article, the deuterium atoms add predominantly to the same (endo) face of the olefins as that coordinated to the dimethylplatinum moiety.
Abstract: Reduction of (diolefin)dialkylplatinum(II) complexes with dihydrogen over a platinum black catalyst is accompanied by interchange of hydrogen among the organic groups and gaseous dihydrogen. Exchange of hydrogens between an alkane solvent and these organic groups also occurs during the reaction, but only relatively slowly. An examination of the stereochemistry of reduction of (norbornadiene)dimethylplatinum(II) with D/sub 2/ indicates that the deuterium atoms add predominantly to the same (endo) face of the olefins as that coordinated to the dimethylplatinum moiety. Reduction of uncomplicated norbornadiene under the same conditions yields norbornane having primarily exo C-D bonds. These experiments are compatible with a mechanism for the reduction involving adsorption of the (diolefin)dialkylplatinum(II) complex on the surface of the platinum catalyst via its platinum atom, conversion of the organic moieties of the soluble (diolefin)dialkylplatinum complex to platinum-surface alkyls, and interchange of hydrogen atoms between these surface alkyls via a mobile pool of platinum-surface hydrogen atoms. Combination of the surface alkyls with surface hydrogen yields alkanes in a final irreversible step. Comparison of the evidence from deuterium-interchange experiments conducted under mass transport limited and reaction rate limited conditions is consistent with the hypothesis that the concentrations of hydrogen on the platinum surface is lower under massmore » transport limited conditions.« less
TL;DR: The direction of cycloaddition to the unsymmetrical carbocycles indene and cyclopentadiene was consistent with the reactions being LUMO (azine)-HOMO (dipolarophile) controlled as discussed by the authors.
Abstract: Thermal reaction (20–70 °C) of the dichloroazine CF 3 CCl=NN=CClCF 3 , 2 , with cyclopentene (in CH 2 Cl 2 solvent), cycloheptene, indene, acenaphthylene, 2,3-dihydrofuran, 3,4-dihydro-2 H -pyran, norbornadiene, cyclopentadiene and dicyclopentadiene afforded, as the major product in each case, the corresponding rearranged [32] cycloadduct 3 containing a CF 3 CCl 2 N= grouping. The direction of cycloaddition to the unsymmetrical carbocycles indene and cyclopentadiene was consistent with the reactions being LUMO (azine)-HOMO (dipolarophile) controlled. On attempted Chromatographic purification on silica gel, the rearranged adducts 3 were hydrolysed to the corresponding amides 4 (=NCCl 2 CF 3 → =NCOCF 3 ). The cyclopentene reaction, unexpectedly, also gave the cyclopentadiene [32] cycloadduct 3b , while from the norbornadiene reaction a hydrolysed 2:1 adduct 9 (4%) was isolated by chromatography. Other products obtained by Chromatographic separation from the 3,4-dihydro-2 H -pyran reaction were the substituted azine CH 2 (CH 2 ) 2 OCH=C-C(CF 3 )=NN=CClCF 3 ( 5 ) (29%), equimolar amounts of the ketone CH 2 (CH 2 ) 2 OCH=C-COCF 3 ( 6 ) (18%) and the chlorohydrazone O(CH 2 ) 4 CH-NHN=CClCF 3 ( 7 ) (18%), possibly arising via the [32] cycloadduct 15 of 5 and the pyran, and the hydrazone CH 2 (CH 2 ) 2 OCH=C-C(CF 3 ) =NNH 2 ( 8 ) (4%), formed via 15 or by hydrolysis of the amide 4g . Treatment of amide 4d , derived from indene with ethanolic methylamine, gave the expected amino compound 21a (94%) and CF 3 CONHMe ( 22 ) (91%). In contrast, treatment of the exo -amide 4h , derived from norbornadiene with ethanolic methylamine, afforded the N -formyl compound 23 (87%), while corresponding treatment of a mixture of the exo - and endo -amides ( 4h and 4i ) gave the exo - and endo -amino compounds ( 21b and 21c ) (88%), together with compound 22 (ca. 10%) and the azapropenylindazole 24 (ca. 5%) ; compound 24 hydrolysed to 23 on storage. It is proposed that the amines 21b and 21c arose mainly via the sequence: =NCOCF 3 → =N-CH=NMe ( 24 ) → =NCHO ( 23 ) → =NH.