Rochat Raphaël, Yamamoto Koji, Lopez Michael J, Nagae Haruki, Tsurugi Hayato, Mashima Kazushi
Department of Chemistry, Graduate School of Engineering Science, Osaka University and CREST, JST, Toyonaka, Osaka 560-8531 (Japan).
Chemistry. 2015 May 26;21(22):8112-20. doi: 10.1002/chem.201500179. Epub 2015 Mar 26.
Organomagnesium complexes 2 were synthesized from N,N-dialkylamineimine ligands 1 and dibenzylmagnesium by benzylation of the imine moiety. 3-Aryl-1-propynes reacted with 2 to form the corresponding tetraalkynyl complexes, which acted as catalysts for the transformation of these terminal alkynes into allenes and further to internal alkynes under mild conditions. To the best of our knowledge, this example is the first of an organomagnesium-catalyzed isomerization of alkynes. Notably, the reactions proceeded through temporally separated autotandem catalysis, thus allowing the isolation of the allene or internal alkyne species in good yields. Mechanistic experiments suggested that the catalytically active tetraalkynyl complexes consist of a tautomeric mixture of alkynyl-, allenyl-, and propargylmagnesium species.
有机镁配合物2是由N,N-二烷基胺亚胺配体1和二苄基镁通过亚胺部分的苄基化反应合成的。3-芳基-1-丙炔与2反应形成相应的四炔基配合物，该配合物在温和条件下可作为催化剂，将这些末端炔烃转化为丙二烯，并进一步转化为内炔烃。据我们所知，该例子是首例有机镁催化的炔烃异构化反应。值得注意的是，反应通过时间上分离的自串联催化进行，从而能够以良好的产率分离出丙二烯或内炔烃物种。机理实验表明，具有催化活性的四炔基配合物由炔基、烯丙基和炔丙基镁物种的互变异构混合物组成。
