We synthesized a series of small symmetrical unsaturated disulfides by a multi-step reaction starting from organic alcohols, and we performed a preliminary test to evaluate the effect of these compounds on the viability of A549 lung cancer cells. The garlic-derived natural compound diallyl disulfide, known for its anticancer activity, was used as the lead compound in this study. We synthesized five
Catalytic Enantioselective Claisen Rearrangements of O-Allyl β-Ketoesters
作者:Christopher Uyeda、Andreas R. Rötheli、Eric N. Jacobsen
DOI:10.1002/anie.201005183
日期:2010.12.10
A chiral guanidinium ion is shown to catalyze enantioselective Claisenrearrangements of O‐allyl β‐ketoesters in 78–87 % ee (see scheme). The pericyclic nature of the process allows products containing vicinal stereogenic centers to be accessed with both enantio‐ and diastereocontrol.
手性胍离子在 78-87% ee 中催化O-烯丙基 β-酮酯的对映选择性克莱森重排(见方案)。该过程的周环性质允许通过对映和非对映控制访问含有邻位立体中心的产品。
Transition-State Charge Stabilization through Multiple Non-covalent Interactions in the Guanidinium-Catalyzed Enantioselective Claisen Rearrangement
作者:Christopher Uyeda、Eric N. Jacobsen
DOI:10.1021/ja110842s
日期:2011.4.6
mechanism by which chiral arylpyrrole-substituted guanidinium ions promote the Claisenrearrangement of O-allyl α-ketoesters and induce enantioselectivity was investigated by experimental and computational methods. In addition to stabilization of the developing negative charge on the oxallyl fragment of the rearrangement transition state by hydrogen-bond donation, evidence was obtained for a secondary
Conceptually novel homolytic substitutions (SH2) of ClCp2Ti−O bonds with benzylic, secondary and tertiary alkyl radicals are described. The intermediates and crucial transition structures were studied by DFT methods. The resulting atom economical radicaltandemreaction can be utilized for the synthesis of structurally complex tetrahydrofurans from simple starting materials and is therefore of interest
Aza-[2,3]-Wittig sigmatropic rearrangement of crotyl amines
作者:James C. Anderson、D. Craig Siddons、Stephen C. Smith、Martin E. Swarbrick
DOI:10.1039/c39950001835
日期:——
The first example of an acyclic aza-[2,3]-Wittig sigmatropic rearrangement is presented, and its application to the synthesis of unnatural amino acids is described.