CP 2 TiCl 2 -catalyzed hydroalumination of internal alkynes: an access to ( Z )-olefins
作者:Arnaud Parenty、Jean-Marc Campagne
DOI:10.1016/s0040-4039(01)02402-9
日期:2002.2
The reduction of alkynols with LiAlH4 in diglyme is a long known process leading to the formation of (E)-alkenols. We have, by serendipity, found that, in the presence of a catalytic amount (10%) of Cp2TiCl2. the stereoselectivity of the reaction is reversed, leading to the selective formation of the (Z)-alkenols. The scope and limitations of this methodology and a postulated catalytic cycle are also discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.
Photochemical Synthesis of 3-Alkynals from 1-Alkynoxy-9,10-anthraquinones
作者:Ronald L. Blankespoor、Peter J. Boldenow、Eric C. Hansen、Jeffrey M. Kallemeyn、Andrew G. Lohse、David M. Rubush、Derek Vrieze
DOI:10.1021/jo900298y
日期:2009.5.15
Photolysis of 1-(3-alkynoxy)-9,10-anthraquinones in deoxygenated methanol leads to moderate yields (35-45%) of 3-alkynals along with the unexpected formation of diacetals. Reaction of these 3-alkynals with Grignard and Wittig reagents occurs nearly quantitatively without rearrangement to their 2,3-dienal isomers.
Synthesis of substituted furans by palladium-catalyzed cyclization of acetylenic ketones
Palladium-catalyzed cyclization of beta,gamma-acetylenic ketones gives furans by intramolecular oxypalladation and subsequent protodemetalation. 3-Allylfurans were exclusively obtained by trapping the intermediate 3-furyl-palladium species with allyl halides in the presence of 2,2-dimethyloxirane as a proton scavenger.
The catalytic action of trimethylgallium on the reaction of alkynyllithium with epoxides