Versatile approach to densely substituted isoxazolines and pyrazolines: Focus on a quaternary carbon center as a constitutive feature
摘要:
A new family of isoxazolines has been obtained via 1,3-dipolar cycloaddition in good to high yields under mild conditions. Our approach focused on construction of the heterocyclic ring and direct access to a quaternary carbon center at position 5. The methodology has also been extended to pyrazoline analogues. The antibacterial activity of these compounds was evaluated, showing specific antibacterial activity against Staphylococcus aureus. Six members of these heterocycles exhibited MIC values of 4 mu g/mL. (C) 2020 Elsevier Ltd. All rights reserved.
cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO4)2 complex of an N,N′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1
The double 1,3-dipolar cycloaddition of allenoates with nitrilimines has been achieved under mild reaction conditions, affording a variety of spirobidihydropyrazoles in moderate to excellent yields with excellent diastereoselectivities. The reaction diastereoselectively constructs double dihydropyrazole moieties and two chiral centers including a spiro carbon center.
A [4 + 3] Annulation Reaction of aza-<i>o</i>-Quinone Methides with Arylcarbohydrazonoyl Chlorides for Synthesis of 2,3-Dihydro-1<i>H</i>-benzo[<i>e</i>][1,2,4]triazepines
An unprecedented [4 + 3] annulation reaction of aza-ortho-quinone methides with arylcarbohydrazonoyl chlorides has been achieved under mild conditions. The annulation underwent a sequential conjugate addition/intramolecular annulation/rearrangement, providing a useful method for the synthesis of biologically interesting 2,3-dihydro-1H-benzo[e][1,2,4]triazepine.
在温和的条件下,已完成了氮杂-邻苯醌甲基化物与芳基羰基肼基甲酰氯的前所未有的[4 + 3]环化反应。进行连续的共轭加成/分子内的成环/重排,为生物上有趣的2,3-二氢-1 H-苯并[ e ] [1,2,4]三氮杂卓合成提供了有用的方法。
Sequential [3+2] annulation reaction of prop-2-ynylsulfonium salts and hydrazonyl chlorides: synthesis of pyrazoles containing functional motifs
A novel sequential [3+2] annulation reaction has been developed using prop-2-ynylsulfonium salts and hydrazonyl chlorides, affording a series of pyrazoles with functional motifs that can be post modified in the preparation of various drugs or drug candidates. Further transformation and gram-scale operations could also be achieved efficiently.
A palladium-catalyzed three-component carbonylative reaction for the synthesis of 3H-1,2,4-triazol-3-ones from hydrazonoyl chlorides and NaN3 has been achieved. The reaction presumably proceeds through a cascadecarbonylation, acyl azide formation, Curtius rearrangement, and intramolecular nucleophilic addition sequence. A wide variety of structurally diverse 3H-1,2,4-triazol-3-ones were constructed
已实现了钯催化的三组分羰基化反应,该反应可从酰氯和NaN 3合成3 H -1,2,4-三唑-3-酮。该反应大概通过级联羰基化,酰基叠氮化物形成,Curtius重排和分子内亲核加成序列进行。以中等至优异的产率构建了各种结构多样的3 H -1,2,4-三唑-3-酮。1,2,3,5-三甲酸三苯酯(TFBen)被用作固体和方便的一氧化碳替代物。