Herein,we report an organocatalytic asymmetric[8+2]higher-order cycloaddition of tropones with azlactones employing bifunctional guanidines as hydrogen-bond-mediated catalysts via a 1,8-addition/annulation process.The...Herein,we report an organocatalytic asymmetric[8+2]higher-order cycloaddition of tropones with azlactones employing bifunctional guanidines as hydrogen-bond-mediated catalysts via a 1,8-addition/annulation process.The reaction has a broad scope with respect to both cycloaddition partners and hence offers rapid access to an array of[5.3.0]bicyclic compounds with excellent outcomes[up to 95%yield,>19:1 diastereomeric ratio(dr),and 96%enantiomeric excess(ee)].Besides,the synthetic utility of the protocol provides rapid transformation into enantioenrichedα-amino acid derivatives.Moreover,the isolated[1,5]-H shift isomer,X-ray crystal structure of chiral guanidinium salt,and density functional theory(DFT)calculations provide convincing evidence for the interpretation of diastereo-and enantioselection.展开更多
Condensation of 3,7-dichloromethyl-5-isopropyl-2-methoxytropane 4 with bis (mercaptoethyl) ether 5a and mono, di, and tri-ethylene glycol bis(mercaptoethyl) ethers 5b-5d gave troponoid-annexed dithiocrown ethers 6a-6d...Condensation of 3,7-dichloromethyl-5-isopropyl-2-methoxytropane 4 with bis (mercaptoethyl) ether 5a and mono, di, and tri-ethylene glycol bis(mercaptoethyl) ethers 5b-5d gave troponoid-annexed dithiocrown ethers 6a-6d. Compounds 6a-6d have selective and reversible mercury salt capturing ability.展开更多
文摘Herein,we report an organocatalytic asymmetric[8+2]higher-order cycloaddition of tropones with azlactones employing bifunctional guanidines as hydrogen-bond-mediated catalysts via a 1,8-addition/annulation process.The reaction has a broad scope with respect to both cycloaddition partners and hence offers rapid access to an array of[5.3.0]bicyclic compounds with excellent outcomes[up to 95%yield,>19:1 diastereomeric ratio(dr),and 96%enantiomeric excess(ee)].Besides,the synthetic utility of the protocol provides rapid transformation into enantioenrichedα-amino acid derivatives.Moreover,the isolated[1,5]-H shift isomer,X-ray crystal structure of chiral guanidinium salt,and density functional theory(DFT)calculations provide convincing evidence for the interpretation of diastereo-and enantioselection.
文摘Condensation of 3,7-dichloromethyl-5-isopropyl-2-methoxytropane 4 with bis (mercaptoethyl) ether 5a and mono, di, and tri-ethylene glycol bis(mercaptoethyl) ethers 5b-5d gave troponoid-annexed dithiocrown ethers 6a-6d. Compounds 6a-6d have selective and reversible mercury salt capturing ability.
