Unsaturated Four-Membered Rings: Efficient Strategies for the Construction of Cyclobutenes and Alkylidenecyclobutanes
作者:Michael Eisold、Andreas N. Baumann、Gabriel M. Kiefl、Sebastian T. Emmerling、Dorian Didier
DOI:10.1002/chem.201604585
日期:2017.1.31
studies of the diastereo‐ and enantioselective formation of strained alkylidenecycloalkanes drove us to more‐thoroughly investigate the formation of four‐membered rings for which only few efficient methods are described. We first developed a strategy to diversify the saturated part of the four‐membered ring and applied it to a highly diastereoselective synthesis of more‐elaborate alkylidenecyclobutanes,
Highly Diastereoselective Synthesis of Methylenecyclobutanes by Merging Boron‐Homologation and Boron‐Allylation Strategies
作者:Michael Eisold、Dorian Didier
DOI:10.1002/anie.201507444
日期:2015.12.21
A highlydiastereoselectivesynthesis of methylenecyclobutanes possessing a quaternary stereocenter is reported, in which boronhomologation of an easily‐generated cyclobutenylmetal species is performed, followed by an allylation reaction. Combining three steps in a one‐pot process further optimized the method, which afforded the expected adducts in excellent yields and stereoselectivity, starting
Enantioenriched alkylidenecyclobutanes possessing a quaternary stereogenic center, usually difficult to access, have been synthesized by combining a double boron-homologation and an allylboration through a highly efficient and diastereoselective one-pot process. Starting from commercially available substrates, this protocol represents a simple way of accessing chiral unsaturated four-membered ring