Atom-Economical Ni-Catalyzed Diborylative Cyclization of Enynes: Preparation of Unsymmetrical Diboronates
作者:Natalia Cabrera-Lobera、M. Teresa Quirós、William W. Brennessel、Michael L. Neidig、Elena Buñuel、Diego J. Cárdenas
DOI:10.1021/acs.orglett.9b02485
日期:2019.8.16
We report a Ni-catalyzed diborylative cyclization of enynes that affords carbo- and heterocycles containing both alkyl- and alkenylboronates. The reaction is fully atom-economical, shows a broad scope, and employs a powerful and inexpensive catalytic Ni-based system. The reaction mechanism seems to involve activation of the enyne by Ni(0) through oxidative cyclometalation of the enyne prior to diboron
The role of cyclobutenes in gold(i)-catalysed skeletal rearrangement of 1,6-enynes
作者:Ana Escribano-Cuesta、Patricia Pérez-Galán、Elena Herrero-Gómez、Masaki Sekine、Ataualpa A. C. Braga、Feliu Maseras、Antonio M. Echavarren
DOI:10.1039/c2ob25419k
日期:——
electron-donating substituents at the alkyne undergo gold(I)-catalysed single cleavage skeletal rearrangement, whereas substrates with electron-withdrawing substituents evolve selectively to double cleavage rearrangement. Theoretical calculations provide a qualitative rationale for these effects, and suggest that bicyclo[3.2.0]hept-5-enes are involved as intermediates. We provide the first X-ray structural evidence