Enantioselective Alkynylation of Aldehydes with 1-Haloalkynes Catalyzed by Tethered Bis(8-quinolinato) Chromium Complex
摘要:
The first example of Cr-catalyzed asymmetric alkynylation of aldehydes with 1-iodo- and 1-bromoalkynes was developed. The use of tethered bis(8-quinolinato) chromium catalyst (3 mol %) allowed preparation of enantioenriched propargyl alcohols with good yields and enantioselectivities up to 92% ee. 1-Bromoalkynes can be activated by the introduction of a cobalt porphine co-catalyst, which enables shorter reaction times without any loss of enantiocontrol.
Gold-Catalyzed Hydrophenoxylation of Propargylic Alcohols and Amines: Synthesis of Phenyl Enol Ethers
作者:Victor Laserna、Catherine Jeapes Rojas、Tom D. Sheppard
DOI:10.1021/acs.orglett.9b01208
日期:2019.6.21
A practical method for the synthesis of phenyl enol ethers is reported. The combination of a gold(I) catalyst and potassium carbonate selectively mediates the addition of phenols to propargylic alcohols/amines in a chemo-, regio-, and stereoselective fashion in high yield. The resulting enol ethers are formed exclusively with a Z-configuration and can be obtained from a wide array of phenols and propargylic
Gold- and Silver-Catalyzed Reactions of Propargylic Alcohols in the Presence of Protic Additives
作者:Matthew N. Pennell、Peter G. Turner、Tom D. Sheppard
DOI:10.1002/chem.201102830
日期:2012.4.10
secondary and tertiary propargylicalcohols undergo a Meyer–Schusterrearrangement to give enones at room temperature in the presence of a gold(I) catalyst and small quantities of MeOH or 4‐methoxyphenylboronic acid. The syntheses of the enone natural products isoegomaketone and daphenone were achieved using this reaction as the key step. The rearrangement of primary propargylicalcohols can readily be combined
Abstract A practical synthesis of propargylic alcohols was developed by alkynylation of aldehydes mediated by zinc and allylbromide. Aromatic, aliphatic and vinyl aldehydes react with phenylacetylene or 1-hexyne to obtain various propargylic alcohols at room temperature in up to 98% yield. This method is characterized with inexpensive materials, wide substrate scope, and mild reaction conditions,
作者:Somsuvra Banerjee、Shivhar B. Ambegave、Ravindra D. Mule、Beeran Senthilkumar、Nitin T. Patil
DOI:10.1021/acs.orglett.0c01596
日期:2020.6.19
By applying the “interplay” mode, which consolidates two key reactivity modes of gold catalysis, namely π-activation mode and cross-coupling mode, the first alkynylative Meyer–Schuster rearrangement is designed and successfully implemented. The current protocol gives straightforward access to enynones, a highly valuable building block, from easily available propargyl alcohol feedstocks. Control experiments