Expeditious Metal-Free Access to Functionalized Polycyclic Acetals under Mild Aqueous Conditions
摘要:
A facile approach for the synthesis of furopyrans and bicyclic bisacetals under mild aqueous conditions is described. This potentially green, diversity oriented approach involves cascade Michael addition and cycloacetalization of pyranones and 1,3-dicarbonyls. An interesting switch in the product class was observed depending on the type of pyranone employed. Products of type I and II obtained herein are an integral part of several bioactive natural products and medicinally interesting compounds.
catalytic methods for the oxidative furan-recyclizations remain scarcely investigated. Given this, we report a means of manganese-catalyzed oxidations of furan with low loading, achieving the Achmatowiczrearrangement in the presence of hydrogen peroxide as an environmentally benign oxidant under mild conditions with wide functional group compatibility.
Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products
作者:Hao-Yuan Wang、Ka Yang、Scott R. Bennett、Sheng-rong Guo、Weiping Tang
DOI:10.1002/anie.201503151
日期:2015.7.20
A highly stereoselective dynamickineticisomerization of Achmatowiczrearrangementproducts was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio‐ and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers.
Lipase B from Candida antarctica catalyzes the oxidative ring expansion of furfuryl alcohols using aqueous hydrogen peroxide to yield functionalized pyranones under mild conditions. The method further allows for the preparation of corresponding piperidinone derivatives by enzymatic rearrangement of N-protected furfurylamines.
来自南极念珠菌的脂肪酶 B 使用过氧化氢水溶液催化糠醇的氧化扩环,在温和条件下产生官能化的吡喃酮。该方法还允许通过N-保护的糠胺的酶促重排来制备相应的哌啶酮衍生物。
Alcohol dehydrogenases can act as powerful catalysts in the preparation of opticallypure γ-hydroxy-δ-lactones by means of an enantioconvergent dynamic redox isomerization of readily available Achmatowicz-type pyranones. Imitating the traditionally metal-mediated "borrowing hydrogen" approach to shuffle hydrides across molecular architectures and interconvert functional groups, this chemoinspired and
作者:Daniel Thiel、Fabian Blume、Christina Jäger、Jan Deska
DOI:10.1002/ejoc.201800333
日期:2018.6.7
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