Environmentally benign, one-pot synthesis of pyrans by domino Knoevenagel/6π-electrocyclization in water and application to natural products
作者:Ene Jin Jung、Byung Ho Park、Yong Rok Lee
DOI:10.1039/c0gc00265h
日期:——
In water medium, environmentally benign, facile, and efficient synthesis of pyrans was achieved in good yields by the reactions of a variety of cyclic 1,3-dicarbonyls with several α,β-unsaturated aldehydes. The key strategy was a formal [3+3] cycloaddition by domino Knoevenagel/6Ï- electrocyclization. This methodology was applied to the synthesis of biologically interesting pyranocoumarin, pyranoquinolinone, and pyranonaphthoquinone derivatives along with selected natural and non-natural products.
Green One-Pot Synthesis of 2H-Pyrans Under Solvent-Free Conditions Catalyzed by Ethylenediammonium Diacetate
作者:Martín J. Riveira、Mirta P. Mischne
DOI:10.1080/00397911.2011.594975
日期:2013.1
Abstract Ethylenediammonium diacetate readily catalyzes the Knoevenagel-type condensation between 1,3-dicarbonyl substrates and α,β-unsaturated aldehydes at room temperature undersolvent-freeconditions. This rapid, efficient, and convenient one-pot approach to the synthesis of 2H-pyrans stands as a significant advance over previously reported protocols. This environmentally friendly methodology has
The chemistry of coumarin derivatives, part 2. Reaction of 4-hydroxycoumarin with ?,?-unsaturated aldehydes
作者:Giovanni Appendino、Giancarlo Cravotto、Silvia Tagliapietra、Gian Mario Nano、Giovanni Palmisano
DOI:10.1002/hlca.19900730709
日期:1990.10.31
4-Hydroxycoumarin (= 4-hydroxy-2H-1-benzopyran-2-one) reacts with enals to give 1,2- or 1,4-addition products, depending on the nature and relative location of the substituents on the olefinic double bond (Scheme 2). The resulting adducts further react intra- or intermolecularly, affording dimeric coumarins or pyranocoumarins in the case of 1,2-addition and acetalic pyranocoumarins in the case of 1,4-addition. With
4-羟基香豆素(= 4-羟基-2 H -1-苯并吡喃-2-酮)与烯醛反应生成1,2-或1,4-加成产物,具体取决于烯基上取代基的性质和相对位置双键(方案2)。所得的加合物进一步在分子内或分子间反应,在1,2-加成的情况下提供二聚香豆素或吡喃香豆素,在1,4-加成的情况下提供乙缩醛吡喃香豆素。带有在C(β)处带有烷基的烯醛,仅形成2 H-吡喃并[3,2- c ]香豆素,该反应代表了轻松而直接地进入最近描述的此类具有生物活性的天然产物的类别。
Cyclization reactions of coumarin derivatives: Chemo- and regioselectivity effects of oxygen/sulfur isosteric replacement
We synthesized several sulfur isosters of ferulenol and related prenylcoumarins from Ferula communis preliminary to finding whether the antitubercular activity of these natural compounds might be dissociated from their antithrombin activity. Direct thionation of ferprenine, an instance of “diversity-oriented” synthesis, yielded a mixture of three thiocoumarin derivatives. When 4-hydroxy-2-deoxy-2-thiocoumarin