114423-89-1Relevant academic research and scientific papers
Cyclopentenone formation via hydrogen activation in the reactions of chromium carbene complexes with alkynes
Challener, Cynthia A.,Wulff, William D.,Anderson, Benjamin A.,Chamberlin, Steve,Faron, Katherine L.,Kim, Oak K.,Murray, Christopher K.,Xu, Yao-Chang,Yang, Dominic C.,Darling, Stephen D.
, p. 1359 - 1376 (1993)
The reactions of alkyl chromium carbene complexes with alkynes have been found to give cyclopentenones. Mechanisms are proposed to account for the formation of these products that involve metal hydride intermediates. As has been previously reported for tungsten, molybdenum alkyl complexes have been found to give 1,3-dienes rather than cyclopentenones. The difference between chromium and molybdenum and tungsten may be that a metal hydride intermediate can re-add to an olefin in the case of chromium rather than undergo reductive elimination. A mechanism for the formation of cyclopentenones involving a free vinylketene was ruled out on the basis of an experiment in which the free vinylketene was generated via thermolysis of a cyclobutenone and found not to give a cyclopentenone product but rather an intramolecular [2 + 2] cycloadduct.
Reaction of Alkynes with Cyclopropylcarbene-Chromium Complexes: A Versatile Cycloaddition Reaction for the Construction of Cyclopentenones
Tumer, Seniz U.,Herndon, James W.,McMullen, Leonard A.
, p. 8394 - 8404 (2007/10/02)
The scope and limitations of the reaction between cyclopropylcarbene-chromium complexes and alkynes have been examined.A variety of cyclopropylcarbene complexes and alkynes have been employed in these studies.The reaction appears to be general for most simple alkynes, producing cyclopentenones.A mechanism has been proposed involving metallacyclobutene formation, electrocyclic ring opening, electrocyclic ring closure, CO insertion, alkene insertion, metallacyclopentene fragmentation and cyclopentadienone reduction.The presence of these intermediates has been inferred from the structure of products obtained when the reaction was conducted in acetonitrile instead of dioxane.A trapping experiment employing 1,6-heptadiyne supports the intermediacy of vinylcarbene or vinylketene complexes.
