Cross-metathesis of allyl halides with olefins bearing amide and ester groups
作者:Jeong In Yun、Hyoung Rae Kim、Sang Kyum Kim、Deukjoon Kim、Jongkook Lee
DOI:10.1016/j.tet.2011.11.064
日期:2012.1
generation catalyst (III) efficiently promotes these processes with olefins bearing a Weinreb amide group. Lastly, a reinvestigation of the ester group tolerance of the allyl halide CM with unsaturated esters demonstrated that III serves as an efficient catalyst for these reactions.
Stereoselective synthesis of cis- and trans-2,3-disubstituted eight-membered medium-ring ethers based on Ireland–Claisen rearrangement of 3-alkoxy-2-propenyl glycolate esters and ring-closing olefin metathesis
A simple stereoselective synthesis of cis- and trans-2,3-disubstituted medium-sized cyclic ethers has been developed based on geometry-selective synthesis of 3-alkoxy-2-propenyl glycolate esters, Ireland–Claisen rearrangement of the glycolate esters, and ring-closing olefin metathesis.
2,2,3-Trisubstituted Tetrahydrofurans and 2<i>H</i>-Tetrahydropyrans by Tandem Demethoxycarbonylation−Michael Addition Reactions
作者:Richard A. Bunce、Eric D. Dowdy、R. Shawn Childress、Paul B. Jones
DOI:10.1021/jo971600s
日期:1998.1.1
A tandem demethoxycarbonylation-Michael addition reaction has been developed as a synthetic route to highly functionalized five- and six-membered oxygen heterocycles. Methyl esters, activated toward decarboxylation by a C-2 ethoxycarbonyl group and tethered by a three- or four-atom chain to an acrylate Michael acceptor, have been prepared and used as the cyclization substrates. Treatment of these compounds
Efficient Medium Ring Size Bromolactonization Using a Sulfur-Based Zwitterionic Organocatalyst
作者:Yi An Cheng、Tao Chen、Chong Kiat Tan、Jun Jie Heng、Ying-Yeung Yeung
DOI:10.1021/ja307210n
日期:2012.10.10
Catalytic bromolactonization of long-chain olefinic acids resulting in the efficient synthesis of medium-sized lactones is reported using a zwitterionic catalyst and stoichiometric N-bromosuccinimide halogen source. The reaction was found to be more efficient at 0 degrees C than at room temperature, which could be attributed to the temperature dependence of the zwitterionic catalyst.
Oxygen Effect in the Iodo Lactonization of Unsaturated Carboxylic Acids Leading to 7- to 12-Membered Ring Lactones
作者:Bruno Simonot、Gerard Rousseau
DOI:10.1021/jo00099a019
日期:1994.10
The reaction of omega-alkenoic acids with bis(sym-collidine)iodine(I) hexafluorophosphate led to (iodomethyl) epsilon-caprolactones in good yields (49-75%) and medium ring iodo lactones in low yields (4-5%). The latter compounds have been obtained after introduction of an oxygen atom in the carbon chain. The position of the oxygen appeared important. This oxygen effect was explained by the stabilization of the intermediate iodonium ion by the oxygen atom.