Nonracemically ligated copper hydride can be used to effect tandem S2'/1,2-reductions of racemic Morita-Baylis-Hillman (MBH) acetates to access enantioenriched chiral allylic alcohols with defined olefin geometry. MBH esters, including those with β-substitution, can be transformed to stereodefined enoates by taking advantage of a bulky, oligomeric, in situ generated trialkoxysiloxane leaving group. Finally, an atypical conversion of easily arrived at MBH alcohol derivatives to nonracemic allylic alcohols is disclosed.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/acs.orglett.6b03464 | DOI Listing |
Sci Adv
January 2025
College of Energy Materials and Chemistry, Inner Mongolia University, Hohhot 010021, China.
Hydrides in metal complexes or nanoclusters are typically viewed as electron-withdrawing. Several recent reports have demonstrated the emergence of "electron-donating" hydrides in tailoring the structure, electronic structure, and reactivity of metal nanoclusters. However, the number of such hydrides included in each cluster kernel is limited to one or two.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Institut für Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111 Chemnitz, Germany.
We present a bifunctional catalyst consisting of a copper(I)/N-heterocyclic carbene and an organocatalytic guanidine moiety that enables, for the first time, a copper(I)-catalyzed reduction of amides with H as the terminal reducing agent. The guanidine allows for reactivity tuning of the originally weakly nucleophilic copper(I) hydrides - formed in situ - to be able to react with difficult-to-reduce amides. Additionally, the guanidine moiety is key for the selective recognition of "privileged" amides based on simple and readily available heterocycles in the presence of other amides within one molecule, giving rise to hitherto unknown site-selective catalytic amide hydrogenation.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Research Institute for Science & Technology, Tokyo University of Science, Tokyo 162-8601, Japan.
Chem Sci
December 2024
Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT) Hyderabad 500007 India https://cramhcu.wixsite.com/rambabu-chegondi.
Herein, we present an economical method for highly enantioselective and diastereoselective Cu-BINAP-catalysed reductive coupling of alkoxyallenes with a range of electronically and structurally diverse ketones to afford 1,2-,-diols, using PMHS as the hydride source. This reductive coupling has also been efficiently employed in the enantioselective desymmetrization of prochiral cyclic ketones harboring quaternary centres, in high yields with exclusive diastereoselectivity. Density Functional Theory (DFT) calculations are used to elucidate that the reaction is facilitated by a kinetically favourable "open" -enolate copper-alkoxyallene conformer, occurring at a lower Gibbs free energy barrier (by 3.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
An operationally convenient cobalt-catalyzed one-pot one-step hydrosilylation/hydroboration reaction of arylidenecyclopropanes is developed to access racemic 1,4-borylsilylalkanes. In addition, the corresponding asymmetric reaction is developed with a chiral copper catalyst to prepare 1,4-borylsilylalkanes with high enantioselectivity by a one-pot two-step procedure. Mechanistic studies reveal that this difunctionalization process begins with metal-hydride-catalyzed ring-opening hydrosilylation of arylidenecyclopropanes to generate homoallylsilane intermediates, followed by regio- or enantioselective metal-hydride-catalyzed hydroboration of homoallylsilanes to produce skipped borylsilylalkanes.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!