1879-00-1Relevant articles and documents
α- And β-Functionalized Ketones from 1,3-Dienes and Aldehydes: Control of Regio- And Enantioselectivity in Hydroacylation of 1,3-Dienes
Parsutkar, Mahesh M.,Rajanbabu, T. V.
supporting information, p. 12825 - 12835 (2021/08/30)
Ketones are among the most widely used intermediates in organic synthesis, and their synthesis from inexpensive feedstocks could be quite impactful. Regio- and enantioselective hydroacylation reactions of dienes provide facile entry into useful ketone-bearing chiral motifs with an additional latent functionality (alkene) suitable for further elaboration. Three classes of dienes, 2- or 4-monosubstituted and 2,4-disubstituted 1,3-dienes, undergo cobalt(I)-catalyzed regio- and enantioselective hydroacylation, giving products with high enantiomeric ratios (er). These reactions are highly dependent on the ligands, and we have identified the most useful ligands and reaction conditions for each class of dienes. 2-Substituted and 2,4-disubstituted dienes predominantly undergo 1,2-addition, whereas 4-substituted terminal dienes give highly enantioselective 4,1- or 4,3-hydroacylation depending on the aldehyde, aliphatic aldehydes giving 4,1-addition and aromatic aldehydes giving 4,3-addition. Included among the substrates are feedstock dienes, isoprene (US$1.4/kg) and myrcene (US$129/kg), and several common aldehydes. We propose an oxidative dimerization mechanism that involves a Co(I)/Co(III) redox cycle that appears to be initiated by a cationic Co(I) intermediate. Studies of reactions using isolated neutral and cationic Co(I) complexes confirm the critical role of the cationic intermediates in these reactions. Enantioselective 1,2-hydroacylation of 2-trimethylsiloxy-1,3-diene reveals a hitherto undisclosed route to chiral siloxy-protected aldols. Finally, facile syntheses of the anti-inflammatory drug (S)-Flobufen (2 steps, 92% yield, >99:1 er) and the food additive (S)-Dihydrotagetone (1 step, 83% yield; 96:4 er) from isoprene illustrate the power of this method for the preparation of commercially relevant compounds.
gamma-alkenyl ketone and preparation method thereof
-
Paragraph 0031; 0156-0159, (2020/02/29)
The invention discloses a gamma-alkenyl ketone preparation method, wherein the target product can be obtained at high yield and high regioselectivity by using acetophenone and 1,3-butadiene as raw materials in the presence of an organic solvent, a catalyst, an additive and a ligand. According to the invention, the method has advantages of high atom economy, high regioselectivity, high yield and the like, can achieve the efficient conversion from a cheap basic organic chemical product 1,3-butadiene to high-added-value gamma-alkenyl ketone, and uses the cheap catalyst, so that the reaction conditions are neutral and mild, and the experimental operation is safe and simple; and the synthesized gamma-alkenyl ketone is a useful synthetic intermediate, can be subjected to a series of conversionsto obtain a series of drug molecule precursors or key intermediates, and has wide application prospect.
Synthesis of dihydrotagetone (2,6-dimethyloct-7-en-4-one)
McAndrew,Riezebos
, p. 367 - 369 (2007/10/12)
The acyclic monoterpene dihydrotagetone (2,6-dimethyloct-7-en-4-one) has been prepared from isobutyl methyl ketone in two stages. The key step involves a simple extension of the Carroll reaction.
