3893-15-0Relevant articles and documents
Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen-Bond-Donor/Lewis Acid Co–Catalyzed, Enantioselective Proton-Transfer
Metternich, Jan B.,Reiterer, Martin,Jacobsen, Eric N.
, p. 4092 - 4097 (2020/09/01)
We report an enantioselective Nazarov cyclization catalyzed by chiral hydrogen-bond-donors in concert with silyl Lewis acids. The developed transformation provides access to tri-substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π-electrocyclization C?C bond-forming step followed by rate- and enantio-determining proton-transfer as the mode of catalysis. (Figure presented.).
Gold(I)-Catalyzed 1,3-Carbofunctionalizations of Anthranils with Vinyl Propargyl Esters to Yield 1,3-Dihydrobenzo[ c]-isoxazoles
Skaria, Manisha,Sharma, Pankaj,Liu, Rai-Shung
supporting information, p. 2876 - 2879 (2019/04/30)
This work describes gold-catalyzed 1,3-carbofunctionalizations of anthranils with vinyl propargyl esters to form 1,3-dihydrobenzo[c]-isoxazoles. Excellent diastereoselectivity has been achieved to yield products containing three stereogenic carbons. These
A synthetic route to 4-alkyl-α-methylhydrocinnamylaldehydes
Vrbková, Eva,Vysko?ilová, Eli?ka,Rott, Martin,Zapletal, Martin,?erveny, Libor
, p. 2603 - 2613 (2017/03/22)
The 4-Alkyl-α-methylhydrocinnamylaldehydes (alkyl-isopropyl, isobutyl, methyl) are frequently used fragrances with desired floral (lilac, cyclamen, lily-of-the-valley) scent. These substances are valued for their good stability in basic solution and, therefore, are frequently used in soaps, detergents, or shampoos. These substances are synthesized by a two-step synthesis involving base catalyzed aldol condensation of 4-alkylbenzaldehyde with propanal followed by selective hydrogenation of the C=C bond. In aldol condensation, selectivity is decreased by formation of undesired products of propanal autocondensation 2-methylpent-2-enal. In this work the reaction conditions for homogenous catalyzed aldol condensation of 4-isobutylbenzadehyde with propanal were tested (catalyst type and amount, molar ratio of reactants, solvent type). Reaction conditions giving the best results (92% conversion, 79% selectivity) were adapted to other 4-alkyl-α-methylcinnamylaldehydes preparation with similar results. In the second step—hydrogenation of aldol product different types of catalyst (nickel, cobalt, palladium or Adkins catalyst), and also different solvents, were tested. Hydrogenation conditions leading to the highest yield (72% selectivity at 95% conversion) were adapted to other 4-alkylhydrocinnamyladehydes with similar results.