A nickel-catalyzed cross-coupling of alkenyl methyl ethers with Grignard reagents, undermildconditions, is described. These conditions allowed access to various stilbenes and heterocyclic stilbenic derivatives as well as to a potential anticancer agent DMU-212.
Methods for the synthesis of phenylacetaldehydes (oxidation, one-carbon chain extension) were compared by using the synthesis of 4-methoxyphenylacetaldehyde as a model example. Oxidations of 4-methoxyphenylethanol with activated DMSO (Swern oxidation) or manganese dioxide gave unsatisfactory results; whereas oxidation with 2-iodoxybenzoic acid (IBX) produced 4-methoxyphenylacetaldehyde in reasonable
Z-selective, anti-Markovnikov addition of alkoxides to terminal alkynes: an electron transfer pathway?
作者:James Cuthbertson、Jonathan D. Wilden
DOI:10.1016/j.tet.2015.04.038
日期:2015.6
Potassium alkoxides undergo anti-Markovnikov addition to aryl-substituted alkynes with Z selectivity in DMF as the solvent. The yields and efficiency of the reaction was also found to be enhanced by the addition of a secondary amine ligand such as N,N'-dimethylethylenediamine. Mechanistic investigations suggest that the products, reaction rates and selectivity can be explained via a single electron transfer from the alkoxide to the alkyne. This leads to a radical anion intermediate, which then rapidly combines with the alkoxide to yield a vinyl anion whose lifetime governs the E:Z selectivity observed in the products. (C) 2015 The Authors. Published by Elsevier Ltd.