Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
作者:Lujia Mao、Rüdiger Bertermann、Katharina Emmert、Kálmán J. Szabó、Todd B. Marder
DOI:10.1021/acs.orglett.7b03294
日期:2017.12.15
An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as
Synthesis of Unsymmetrically Substituted 1,3-Butadiynes and 1,3,5-Hexatriynes via Alkylidene Carbenoid Rearrangements
作者:Annabelle L. K. Shi Shun、Erin T. Chernick、Sara Eisler、Rik R. Tykwinski
DOI:10.1021/jo026481h
日期:2003.2.1
Unsymmetrically substituted 1,3-butadiynes and 1,3,5-hexatriynes are synthesized in four steps from commercially available aldehydes or carboxylic acids. The key step in this process involves a Fritsch-Buttenberg-Wiechell rearrangement, in which an alkylidene carbenoid intermediate subsequently rearranges to the desired polyyne. This rearrangement proceeds under mild conditions, and it is tolerant
A copper-based catalyst system for the direct coupling of polyfluoroarenes with propargyl phosphates has been developed. The catalysis can provide a rapid and concise access to (polyfluoroaryl)allenes, which can be important building blocks for the synthesis of fluorinated functional materials.
magnesium metal in the presence of chlorotrimethylsilane in N,N-dimethylformamide (DMF) gave silyl allenol ethers or β-silyl enones. Isolation of silyl allenol ethers was found to require a careful treatment and only hydrolyzed β-silyl enones were formed in some cases. Diverse multisubstituted allenol silylethers and β-silyl enones with good functional group tolerance were selectively synthesized in 38–86%
An asymmetric linear alkyl alkyne addition to aromatic aldehydes catalyzed by the Ti-(R)-BINOL system is reported with high enantioselectivity and yield. Our study expands upon the synthetic scope of propargylic alcohols, which could serve as potentially useful intermediates for the synthesis of various natural products. (C) 2011 Elsevier Ltd. All rights reserved.