Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
2-Benzothiazolyl Propargyl Sulfides: Versatile Precursors for Enantiopure Allenes, E-α,β-Unsaturated Ketones and Z-Sulfonylalkenes
作者:Dagmar Kapeller、Philip Kocienski
DOI:10.1055/s-0030-1258259
日期:2010.11
described. The approach proceeds via a retro-ene reaction, initiated by lithium aluminium hydride mediated cleavage of benzothiazole from the respective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As such, allenes in up to 92% yield are formed under evolution of sulfur dioxide at ambienttemperature. Furthermore, a new and mild way to generate E-α,β-unsaturated ketones has been discovered. These
Cu(I)-catalyzed anti-SN2′-type reduction of internal propargylic carbonates with hydrosilanes affords various di- and trisubstituted allenes with high regioselectivities; the reactions are compatible with functional groups and work efficiently for the synthesis of optically-active allenes.
CuI-Catalyzed Cross-Coupling of <i>N</i>-Tosylhydrazones with Terminal Alkynes: Synthesis of 1,3-Disubstituted Allenes
作者:Mohammad Lokman Hossain、Fei Ye、Yan Zhang、Jianbo Wang
DOI:10.1021/jo3024686
日期:2013.2.1
A CuI-catalyzedsynthesis of 1,3-disubstituted allenesfrom1-alkynes by the reaction with various N-tosylhydrazones has been developed. This method, which uses readily available starting materials and is operationally simple, offers 1,3-disubstituted allenes in moderate to good yields. The reaction also tolerates various functional groups.
Palladium-Catalyzed Chemoselective Allylic Substitution, Suzuki-Miyaura Cross-Coupling, and Allene Formation of Bifunctional 2-B(pin)-Substituted Allylic Acetate Derivatives
作者:Byeong-Seon Kim、Mahmud M. Hussain、Nusrah Hussain、Patrick J. Walsh
DOI:10.1002/chem.201402353
日期:2014.9.8
of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium‐based phosphane catalysts and readily available 2‐B(pin)‐substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction