80605-29-4Relevant articles and documents
Novel dienes and dienophiles, VI: On the chemical behavior of Z-ethynyl-1,3-butadiene
Hopf, Henning,Jaeger, Helge,Ernst, Ludger
, p. 815 - 824 (2007/10/03)
The behavior of 2-ethynyl-1,3-butadiene (1) as the diene component in Diels-Alder additions has been studied using a selection of representative double and triple bond dienophiles. The latter include maleic anhydride (5a), diethyl fumarate (6), benzoquinone (7), methyl acrylate (11), juglone (20), 1-methylcyclopropene (23), dimethyl acetylenedicarboxylate (26), propiolic aldehyde (32), 4-phenyl-1,2,4-triazolin-3,5-dione (35) and diethyl azodicarboxylate (37). [2 + 4] Cycloadducts were formed in all cases in varying yields. The addition is accompanied by thermal dimerization of 1 which leads to 1,4-diethynyl-4-vinyl-1-cyclohexene (43) and 1,6-diethynyl-1,5-cyclooctadiene (39). The mechanism of this dimerization is discussed. In a competition experiment towards maleic anhydride (5a), diene 1 was shown to be ca. five times less reactive than isoprene. VCH Verlagsgesellschaft mbH, 1996.
Alkine und Cumulene, XV. Ueber die Photodimerisierung konjugierter Enine
Eisenhuth, Ludwig,Siegel, Herbert,Hopf, Henning
, p. 3772 - 3788 (2007/10/02)
On irradiation in the presence of triplet sensitizers having a triplet energy >250 KJ/mol, vinylacetylene (1a) dimerizes to cis- and trans-1,2-diethynylcyclobutane (cis- and trans-2) as well as minor amounts of 4-ethynyl-1-vinylcyclobutene (3).The effect of substituents on the course of the reaction is investigated: whereas alkyl, vinyl, and phenyl substituents, respectively, in the 4-position of 1a do not influence the photoaddition, 2-substituted enynes yield the corresponding cyclobutanes in poor yields only.Finally, 1-substituted vinylacetylenes (besides the substituents mentioned above the influence of ethynyl, chloro, and methoxy groups has been investigated) do not provide photodimers; they are cis-trans-isomerized instead.The mechanism of the photoaddition is discussed.
