51478-26-3Relevant articles and documents
The Heterogeneous Catalytic Hydrogenation of Cumulated Allene-cyclopropanes: 1-(2'-Methylpropenylidene)-7-bicycloheptane
Cromble, Leslie,Fernando, Candida E. C.
, p. 1501 - 1518 (2007/10/03)
The formation of products from the heterogeneous solution phase catalytic hydrogenation of the title compound 1 in methanol over supported platinum and palladium catalysts has been studied using 'snapshot analysis' graphs. As expected from 'catalyst hindrance' considerations, the major first formed product with both metals is the conjugated cis-olefin-cyclopropane 7, the trans-isomer 8 being made for comparison by sodium in liquid ammonia reduction. Products appear and disappear during the hydrogenations leaving, at the cassation of reaction in the case of platinum catalyst, 75 percent of cyclopropane 6 and 25 percent of saturated hydrocarbon 3. Use of a palladium reverses the quantitative situation - 12 percent cyclopropane 6 and 88 percent of hydrocarbon 3. If in the title allene-cyclopropane structure 1 a methyl is inserted at position 1 of the cyclopropyl as in 13, complete hydrogenation over a palladium catalyst occurs with cleavage of the cyclopropane from the less hindered side forming a quaternary centre 14 in high yield. Catalytic hydrogenation of a related conjugated diene having one double bond cumulated with a cyclopropane ring 12 is also considered. Dimethylallene carbene reacts selectively towards an (E)-linkage of (Z)-(E)-(E)-cyclododeca-1,5,9-triene giving 19 as the crystalline product.
