5-Substituted-2-furan methanols 1a-c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, alpha-methyl allyl acetate, or 1,1-dimethylallene in the presence of an ortho-cyclometalated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3-TUNEPHOS, and (R)-C3-SEGPHOS, respectively. In the presence of 2-propanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a-c are converted to identical products of allylation, crotylation, and tert-prenylation. Optically enriched products of carbonyl allylation, crotylation, and reverse prenylation 3b, 4b, and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding gamma-hydroxy-beta-pyrones 6a-c, respectively, with negligible erosion of enantiomeric excess.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830394 | PMC |
| http://dx.doi.org/10.1021/jo902697g | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Carbonyl Allylation and Crotylation: Historical Perspective, Relevance to Polyketide Synthesis, and Evolution of Enantioselective Ruthenium-Catalyzed Hydrogen Auto-Transfer Processes.
Synthesis (Stuttg)
May 2023
University of Texas at Austin, Department of Chemistry. 105 E 24 St. (A5300), Austin, Tx 78712-1167 (USA).
The evolution of methods for carbonyl allylation and crotylation of alcohol proelectrophiles culminating in the design of iodide-bound ruthenium-JOSIPHOS catalysts is prefaced by a brief historical perspective on asymmetric carbonyl allylation and its relevance to polyketide construction. Using gaseous allene or butadiene as precursors to allyl- or crotylruthenium nucleophiles, respectively, new capabilities for carbonyl allylation and crotylation have been unlocked, including stereo- and site-selective methods for the allylation and crotylation of 1,3-diols and related polyols.
View Article and Find Full Text PDFScalable Total Synthesis of Leucascandrolide A Macrolactone Using a Chiral Phosphoric Acid/CuX Combined Catalytic System.
Org Lett
March 2023
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
A scalable total synthesis of leucascandrolide A macrolactone has been accomplished with a longest linear sequence of 17 steps from readily available feedstocks in 31.2% yield. The key steps in this synthesis are the enantioselective allylation reaction by chiral phosphoric acid (CPA)/CuBr cooperative catalysis and the diastereoselective catalytic crotylation in the presence of CPA with CuCl.
View Article and Find Full Text PDF-Glycosylcrotylboronates for the Synthesis of Glycomimetics.
Org Lett
January 2022
Department of Chemistry, Hunter College, 695 Park Avenue, New York, New York 10065, United States.
The stereoselective synthesis of - and - isomers of a - crotylpinacolboronate Ni-promoted reactions on an allylic acetate and a diene precursor, respectively, is described. The - and - isomers reacted with 1,2--isopropylidene glyceraldehyde in the presence or absence of ()- and ()- TRIP catalysts, to give predominantly 3,4- and 3,4- crotylation products, respectively, with moderate to high facial selectivity. These products were transformed to biologically relevant --disaccharides.
View Article and Find Full Text PDFElectrochemical Synthesis of Allylic Amines from Terminal Alkenes and Secondary Amines.
J Am Chem Soc
December 2021
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
Allylic amines are valuable synthetic targets en route to diverse biologically active amine products. Current allylic C-H amination strategies remain limited with respect to the viable -substituents. Herein, we disclose a new electrochemical process to prepare aliphatic allylic amines by coupling two abundant starting materials: secondary amines and unactivated alkenes.
View Article and Find Full Text PDFTotal Synthesis of Leiodermatolide A via Transfer Hydrogenative Allylation, Crotylation, and Propargylation: Polyketide Construction beyond Discrete Allyl- or Allenylmetal Reagents.
J Am Chem Soc
July 2021
Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Austin, Texas 78712, United States.
The total synthesis of leiodermatolide A was accomplished in 13 steps (LLS). Transfer hydrogenative variants of three carbonyl additions that traditionally rely on premetalated reagents (allylation, crotylation, and propargylation) are deployed together in one total synthesis.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!