A convenient procedure for the synthesis of highly enantioenriched allenylsilanes by Johnson orthoester Claisen rearrangement of 1-silyl propargylic alcohols is described. Allenylsilanes are then used as carbon nucleophiles in three-component, Lewis acid mediated additions to in situ generated oxonium ions, resulting in enantioenriched homopropargylic ethers.
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http://dx.doi.org/10.1021/ol070936d | DOI Listing |
Angew Chem Int Ed Engl
November 2019
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China.
A copper-catalyzed silylation of propargyl dichlorides was developed to access chloro-substituted allenylsilanes under mild reaction conditions. Moreover, enantioenriched chloro-substituted allenylsilanes can be synthesized in moderate to high yields and good enantioselectivities with this protocol.
View Article and Find Full Text PDFOrg Lett
September 2016
Department of Chemistry, Metcalf Center for Science and Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
Highly enantioenriched chiral allenylsilanes 4 were prepared in high yield through a scalable synthetic sequence, employing a modified copper-catalyzed SN2' reaction. These reagents were used for the production of enantioenriched homoproparglylic ethers 5, which were subjected to titanium alkoxide-mediated reductive coupling with acetylenic esters to produce (E,E)-dienes 6 bearing α,β,γ,δ-unsaturated esters. Both enantiomers of nuclear factor of activated T-cells-68 (NFAT-68) were synthesized in five steps with the sequential use of the two methods.
View Article and Find Full Text PDFJ Am Chem Soc
December 2015
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
Copper-catalyzed highly efficient hydrosilylation reaction of enynoates was developed. Under simple reaction conditions, various di-, tri-, and tetrasubstituted racemic allene products could be obtained in high yields. The asymmetric 1,6-addition of silyl group to the (Z)-2-alken-4-ynoates could be achieved under mild reaction conditions to afford the silyl-substituted enantioenriched chiral allene products in good yields and with high enantioselectivities.
View Article and Find Full Text PDFTetrahedron
September 2013
Department of Chemistry, The Scripps Research Institute, Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
The enantiodivergent hydroboration reactions of racemic allenylsilane (±)- with ( Ipc)BH and subsequent crotylboration of achiral aldehydes with the product crotylborane ()-- at -78 °C provide ()--silyl--homoallylic alcohols in 71-89% yield and with 93-96% ee. Intriguingly, mismatched double asymmetric crotylboration reactions of enantioenriched chiral aldehydes with ()-- proceed under Curtin-Hammett control to give -β-hydroxylcrotylsilanes as the only products.
View Article and Find Full Text PDFTetrahedron
July 2013
Department of Chemistry, The Scripps Research Institute, Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
The enantiodivergent hydroboration reactions of racemic allenylsilane (±)- with ( Ipc)BH and subsequent crotylboration of achiral aldehydes with the product crotylborane ()-- at -78 °C provide ()--silyl--homoallylic alcohols in 71-89% yield and with 93-96% ee. Intriguingly, mismatched double asymmetric crotylboration reactions of enantioenriched chiral aldehydes with ()-- proceed under Curtin-Hammett control to give --hydroxylcrotylsilanes as the only products.
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