[reaction: see text] Complex 1 bearing a diphosphinidenecyclobutene ligand (DPCB-OMe) catalyzes highly stereoselective hydrosilylation of diethynylarenes with HSiMe2Ph to afford (Z,Z)-bis(2-silylethenyl)arenes. Treatment of the hydrosilylation products with N-bromosuccinimide causes bromodesilylation in a stereospecific manner, giving (Z,Z)-bis(2-bromoethenyl)arenes in high geometrical purity (>98%).
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jo051908g | DOI Listing |
J Am Chem Soc
December 2024
Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Hydroalkylation of terminal alkynes is a powerful approach to the synthesis of disubstituted alkenes. However, its application is largely unexplored in the synthesis of α,β-unsaturated carbonyls, which are common among synthetic intermediates and biologically active molecules. The thermodynamically less stable -isomers of activated alkenes have been particularly challenging to access because of their propensity for isomerization and the paucity of reliable -selective hydroalkylation methods.
View Article and Find Full Text PDFChem Asian J
November 2024
Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, Telangana, India.
An efficient Mn(III)-promoted phosphorylation of dehydroalanine (Dha) has been developed to give unusual α-amino acids bearing phosphonates/phosphine oxides and β-vinyl phosphonates/phosphinates depending on N-protection of amino acid. N,N-diprotected dehydroalanine reacted with H-phosphonates and H-phosphine oxides to give structurally diverse phosphorylated α-amino acids through conjugate addition of phosphorous radical generated by Mn(OAc).2HO.
View Article and Find Full Text PDFACS Catal
August 2024
Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, Wien A-1060, Austria.
A stereo- and regioselective Mn(I)-catalyzed hydroboration of terminal alkynes with pinacolborane (HBPin) is described. The hydroboration reaction is highly -selective in the case of aryl alkynes and -selective in the case of aliphatic alkynes. The reaction requires no additives or solvents and proceeds with a catalyst loading of 1 mol % at 50-70 °C.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2024
Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
Metal-catalyzed enantioselective conjugate arylations of electron-poor alkenes are highly selective processes for C(sp)-C(sp) bond formation. δ-Selective hydroarylations of electron-poor 1,3-dienes are less well developed and reactions that deliver high enantioselectivity while giving single alkene isomer products are elusive. Here we report the Rh-catalyzed δ-arylation of aryl-substituted 1,3-dienes that gives nearly exclusive Z-1,4-addition products (generally with >95 : 5 positional and geometrical selectivity).
View Article and Find Full Text PDFJ Org Chem
May 2024
CNRS, CiTCoM, Faculté de Pharmacie, Université Paris Cité, 4, avenue de l'Observatoire, F-75006 Paris, France.
In this paper are presented the results of the preliminary studies conducted on two model substrates that allowed the testing of various strategies and set the proper conditions that thereafter culminated in the synthesis of the C1-C23 chain of enacyloxin-IIa and its congeners. Innovative strategic options were explored on each model allowing the stereochemical control of the following two elements: (a) the 2, 4, 6, 8, and 10 chlorinated undecapentaenoic chain, thanks to -selective Kaneda's alkyne allylchlorination and an -selective Pd/Cu allene-alkyne coupling and (b) the unusual - -OH/-Cl/-OCONH 17-19 triad, thanks to a highly diastereoselective Mukaiyama aldol reaction.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!