Study of the stereoselectivity of the nucleophilic epoxidation of 3-hydroxy-2-methylene esters
摘要:
The diastereoselectivity of the nucleophilic epoxidation of 3-hydroxy-2-methylene esters has been studied. The 3-hydroxy-2-methylene esters were obtained through a Morita-Baylis-Hillman reaction. The resulting epoxyesters were treated with thiophenol for transformation into 2,3-dihydroxy-2-((phenylthio)methyl), which upon treatment with triphosgene afforded the corresponding cyclic carbonates. (C) 2013 Elsevier Ltd. All rights reserved.
acid-catalyzed asymmetricBaylis-Hillmanreaction is described. Good to high enantioselectivities were obtained using 3 mol % chiral catalyst. Novel camphor-derived dimerized ligands were prepared from the condensation of (+)-ketopinic acid with the corresponding diamines and hydrazine under acidic conditions. When alpha-naphthyl acrylate was used as a Michael acceptor, the reaction is complete within
Chiral chelating agents and chiral catalysts, which are formed from the chiral chelating agents and metal, are described. One chiral chelating agent has a general formula (1) as illustrated below:
1
wherein R represents H, methyl, ethyl, a primary, secondary or tertiary straight, branched or cyclic alkyl group having 3-7 carbon atoms, a heterocyclic or aromatic group, an aromatic group substituted at the 2-, 3- or 4-position, an aromatic-like group, or a naphthyl or naphthyl-derived group, and n is an integer between 0 and 4.
TiO<sub>2</sub>@UiO-68-CIL: A Metal–Organic-Framework-Based Bifunctional Composite Catalyst for a One-Pot Sequential Asymmetric Morita–Baylis–Hillman Reaction
TiO2@UiO-68-CIL (2) was prepared by impregnating 1 in a toluene solution of Ti(OPri)4 and sequential in situ hydrolysis. The obtained 2 can be a bifunctionalasymmetric heterogeneous catalyst to successfully promote the one-pot Morita–Baylis–Hillman reaction starting from aromatic alcohols in a tandem way.
Key features of the β-isocupreidine (β-ICD)-catalyzed asymmetric Baylis–Hillmanreaction of aldehydes with 1,1,1,3,3,3-hexafluoroisopropyl acrylate (HFIPA) are presented. In addition, an improved method using azeotropically dried β-ICD is described.