Unprecedented <i>E</i>-stereoselectivity on the sigmatropic Hurd–Claisen rearrangement of Morita–Baylis–Hillman adducts: a joint experimental–theoretical study
作者:Vinicius Sobral Silva、Terezinha Alves Tolentino、Tiago Costa Alves Fontoura Rodrigues、Fernanda Ferrari Martins Santos、Daniel Francisco Scalabrini Machado、Wender Alves Silva、Heibbe Cristhian Benedito de Oliveira、Angelo Henrique Lira Machado
DOI:10.1039/c9ob00533a
日期:——
first systematic investigation of the tandem mercury(II) catalysed transvinylation/Hurd–Claisen rearrangement of MBH adducts derived from alkyl acrylates. This is the first report of E-selectivity for MBH adducts with alkyl side chains and is complementary to the previously reported Johnson–Claisen and Eschenmoser–Claisen rearrangements. The rearrangement products were obtained in good yields and could
A concerted method for the stereospecific addition of thiophenol to α, β-unsaturated esters 1 and 3 has been developed. This provides a convenient route for the stereo-selective preparation of less available Z__--α, β-unsaturated esters and lactones 3.
Diphenyl disulfide is shown to be an efficient catalyst for the isomerization of (Z)-2-alkenoic esters to (E)-2-alkenoic esters in boiling tetrahydrofuran.
of the QS-regulated operon vioABCDE. Docking calculations suggested a good correlation between binding affinity energies and inhibition effects, with all molecules positioned within the CviR autoinducer-binding domain (AIBD). The most active lactone yielded the best binding affinity energy, most probably due to its unprecedented binding with the AIBD. Our results show α-alkylidene δ-lactones as promising
Stereospecific nucleophilic addition of thiols to derivatives of alpha,beta-unsaturated carboxylic acids is described. The additions are carried out at room temperature in the presence of a catalytic amount of lithium thiolate and an excess of thiol as a proton source. Erythro and threo adducts are obtained with high diasteroselectivity from E and Z olefins, respectively. This anti addition suggests that the enolate generated by nucleophilic addition undergoes rapid protonation prior to conformational change in the intermediate.