Palladium-Catalyzed Diastereo- and Enantioselective Formal [3 + 2]-Cycloadditions of Substituted Vinylcyclopropanes
作者:Barry M. Trost、Patrick J. Morris、Simon J. Sprague
DOI:10.1021/ja309003x
日期:2012.10.24
We describe a palladium-catalyzeddiastereo- and enantioselectiveformal [3 + 2]-cycloaddition between substituted vinylcyclopropanes and electron-deficient olefins in the form of azlactone- and Meldrum's acid alkylidenes to give highly substitutedcyclopentane products. By modulation of the electronic properties of the vinylcyclopropane and the electron-deficient olefin, high levels of stereoselectivity
Metal-free and benign approach for the synthesis of dihydro-5′<i>H</i>-spiro[benzo[<i>c</i>]chromene-8,4′-oxazole]-5′,6(7<i>H</i>)-dione scaffolds as masked amino acids
作者:Behnaz Shafiee、Joseph Duffield、Rudy Timm、Rohana Liyanage、Jackson O. Lay、Ahmad R. Khosropour、Hadi Amiri Rudbari、M. Hassan Beyzavi
DOI:10.1039/c9gc00428a
日期:——
straightforward, and three-component condensation/cascade reaction of 4-hydroxycoumarins and (Z)-azlactones to construct diversified dihydro-5′H-spiro[benzo[c]chromene-8,4′-oxazole]-5′,6(7H)-diones as new masked amino acid derivatives has been developed with high to excellent yields and regio- and diastereoselectivity. This metal-free reaction proceeds via a one-pot cascade Michael addition/lactoniz
生态友好的,直接的,和4-羟基香豆素三组分缩合/级联反应和(Ž)-azlactones到构建多元化二氢-5' ħ -螺[苯并[ C ^ ]苯并吡喃8,4'-唑] - 5',6(7 H)-二酮作为新的被掩盖的氨基酸衍生物已被开发出来,具有高到极好的产率以及区域和非对映选择性。这种无金属的反应通过使用可重复使用的碳酸亚丙酯作为绿色溶剂的一锅级联迈克尔加成/内酯化/脱羧反应。还进行了放大检查,显示了在反应条件下的高原子经济性。此外,使用同位素标记,LC-MS监测和TLC-MALDI-MS进一步研究了反应机理。
Palladium-Catalyzed Diastereo- and Enantioselective Synthesis of Substituted Cyclopentanes through a Dynamic Kinetic Asymmetric Formal [3+2]-Cycloaddition of Vinyl Cyclopropanes and Alkylidene Azlactones
作者:Barry M. Trost、Patrick J. Morris
DOI:10.1002/anie.201101684
日期:2011.6.27
An enantioselective preparation of vinylcyclopentanes has been achieved through the title reaction (see scheme). A range of aryl, heterocyclic, alkenyl, and alkyl substitutedazlactonealkylidenes have been utilized, giving the cyclopentane products in good yield, diastereomeric ratio, and enantioselectivity.
3-Isothiocyanato Oxindoles Serving as Powerful and Versatile Precursors to Structurally Diverse Dispirocyclic Thiopyrrolidineoxindoles through a Cascade Michael/Cyclization Process with Amino-Thiocarbamate Catalysts
Cascading catalysis: 3‐Isothiocyanato oxindoles act as powerful and versatile precursors for a range of structurally diverse dispirocyclic thiopyrrolidineoxindoles containingtwospiro‐quaternary and threecontiguous stereogenic centers in quantitative yields with excellent disatereo‐ and enantioselectivities by only using 1 mol % amino‐thiocarbamate catalyst.
作者:A. Avenoza、J. H. Busto、C. Cativiela、J. M. Peregrina
DOI:10.1055/s-1995-3973
日期:1995.6
Treatment in an alkaline medium of the cycloadducts obtained from the Diels-Alder cycloaddition of Danishefsky’s diene with different oxazol-5(4H)-ones constitutes an efficient method for the aromatisation of the cyclohexene ring, allowing the synthesis of 3-substituted 4-aminophenols, by previous hydrolysis of the benzamide group.