20626-38-4Relevant academic research and scientific papers
Thermal isomerisations, XXIV. Gas phase kinetics of the pyrolysis of some 3,3-dimethyl-1-alkyl-cyclopropenes: Some surprising substituent activation effects and the intramolecular trapping of vinylidene intermediates
Hopf, Henning,Plagens, Andreas,Walsh, Robin
, p. 825 - 835 (2007/10/03)
The gas phase pyrolyses of four 3,3-dimethyl-1-alkylcyclopropenes were studied for which the 1-alkyl substituents are ethyl- (6), isopropyl- (7), 1′-butyl- (8) and 1′-isoamyl- (9). Rate data over a 50°C temperature range were obtained and Arrhenius parameters are reported both for overall reactions and individual pathways for all compounds. Tests confirm all reactions to be unimolecular and homogeneous. For 8 and 9, noteworthy products are cyclopentenes, whose presence demonstrates the involvement of vinylidene intermediates. The substantial product yields of 2,4-alkadienes together with dramatic rate enhancement effects of these 1-alkyl substituents (relative to 1-methyl) are explained by the involvement of vinylcarbene intermediates in this pathway. Minor, transient products from 6, 8 and 9 are probably isomeric cyclopropenes. This suggests further pathways for vinylidene intermediates, whose reactivity pattern is briefly reviewed. VCH Verlagsgesellschaft mbH, 1996.
Metal Catalysis in Organic Reactions. Part 13. The Reaction of 3-En-1-ynes with Trialkylalanes: Influence of Transition-metal Complexes
Caporusso, Anna Maria,Giacomelly, Giampaolo,Lardicci, Luciano
, p. 1900 - 1908 (2007/10/02)
The reaction between trialkylalanes and 3-alkyl-, or 4-alkyl-, or 3,4-dialkyl-but-3-en-1-ynes (1) lead to products which correspond to metallation, reduction, and carbalumination processes.The extent of such reactions, and the regio- and stereo-selectivity of the carbalumination, are dependent on the enyne used.A mechanism is proposed involving tautomeric equilibria among several α-unsaturated organoaluminium intermediates to explain the formation of the carbalumination products. In the presence of catalytic amounts of nickel and manganese complexes, 3-en-1-ynes (1), by reacting with tri-isobutylaluminium, are dimerized selectively in a 'head-to-tail' fashion to conjugated tetraenes having different structures in relation to the different nature of the transition-metal complex.The preparative aspect of these induced reactions is discussed, and, in the light of previous reports, some mechanistic considerations are presented.
